diff --git a/vendor/golang.org/x/text/transform/transform.go b/vendor/golang.org/x/text/transform/transform.go
new file mode 100644
index 0000000..fe47b9b
--- /dev/null
+++ b/vendor/golang.org/x/text/transform/transform.go
@@ -0,0 +1,705 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package transform provides reader and writer wrappers that transform the
+// bytes passing through as well as various transformations. Example
+// transformations provided by other packages include normalization and
+// conversion between character sets.
+package transform // import "golang.org/x/text/transform"
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"unicode/utf8"
+)
+
+var (
+	// ErrShortDst means that the destination buffer was too short to
+	// receive all of the transformed bytes.
+	ErrShortDst = errors.New("transform: short destination buffer")
+
+	// ErrShortSrc means that the source buffer has insufficient data to
+	// complete the transformation.
+	ErrShortSrc = errors.New("transform: short source buffer")
+
+	// ErrEndOfSpan means that the input and output (the transformed input)
+	// are not identical.
+	ErrEndOfSpan = errors.New("transform: input and output are not identical")
+
+	// errInconsistentByteCount means that Transform returned success (nil
+	// error) but also returned nSrc inconsistent with the src argument.
+	errInconsistentByteCount = errors.New("transform: inconsistent byte count returned")
+
+	// errShortInternal means that an internal buffer is not large enough
+	// to make progress and the Transform operation must be aborted.
+	errShortInternal = errors.New("transform: short internal buffer")
+)
+
+// Transformer transforms bytes.
+type Transformer interface {
+	// Transform writes to dst the transformed bytes read from src, and
+	// returns the number of dst bytes written and src bytes read. The
+	// atEOF argument tells whether src represents the last bytes of the
+	// input.
+	//
+	// Callers should always process the nDst bytes produced and account
+	// for the nSrc bytes consumed before considering the error err.
+	//
+	// A nil error means that all of the transformed bytes (whether freshly
+	// transformed from src or left over from previous Transform calls)
+	// were written to dst. A nil error can be returned regardless of
+	// whether atEOF is true. If err is nil then nSrc must equal len(src);
+	// the converse is not necessarily true.
+	//
+	// ErrShortDst means that dst was too short to receive all of the
+	// transformed bytes. ErrShortSrc means that src had insufficient data
+	// to complete the transformation. If both conditions apply, then
+	// either error may be returned. Other than the error conditions listed
+	// here, implementations are free to report other errors that arise.
+	Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error)
+
+	// Reset resets the state and allows a Transformer to be reused.
+	Reset()
+}
+
+// SpanningTransformer extends the Transformer interface with a Span method
+// that determines how much of the input already conforms to the Transformer.
+type SpanningTransformer interface {
+	Transformer
+
+	// Span returns a position in src such that transforming src[:n] results in
+	// identical output src[:n] for these bytes. It does not necessarily return
+	// the largest such n. The atEOF argument tells whether src represents the
+	// last bytes of the input.
+	//
+	// Callers should always account for the n bytes consumed before
+	// considering the error err.
+	//
+	// A nil error means that all input bytes are known to be identical to the
+	// output produced by the Transformer. A nil error can be be returned
+	// regardless of whether atEOF is true. If err is nil, then then n must
+	// equal len(src); the converse is not necessarily true.
+	//
+	// ErrEndOfSpan means that the Transformer output may differ from the
+	// input after n bytes. Note that n may be len(src), meaning that the output
+	// would contain additional bytes after otherwise identical output.
+	// ErrShortSrc means that src had insufficient data to determine whether the
+	// remaining bytes would change. Other than the error conditions listed
+	// here, implementations are free to report other errors that arise.
+	//
+	// Calling Span can modify the Transformer state as a side effect. In
+	// effect, it does the transformation just as calling Transform would, only
+	// without copying to a destination buffer and only up to a point it can
+	// determine the input and output bytes are the same. This is obviously more
+	// limited than calling Transform, but can be more efficient in terms of
+	// copying and allocating buffers. Calls to Span and Transform may be
+	// interleaved.
+	Span(src []byte, atEOF bool) (n int, err error)
+}
+
+// NopResetter can be embedded by implementations of Transformer to add a nop
+// Reset method.
+type NopResetter struct{}
+
+// Reset implements the Reset method of the Transformer interface.
+func (NopResetter) Reset() {}
+
+// Reader wraps another io.Reader by transforming the bytes read.
+type Reader struct {
+	r   io.Reader
+	t   Transformer
+	err error
+
+	// dst[dst0:dst1] contains bytes that have been transformed by t but
+	// not yet copied out via Read.
+	dst        []byte
+	dst0, dst1 int
+
+	// src[src0:src1] contains bytes that have been read from r but not
+	// yet transformed through t.
+	src        []byte
+	src0, src1 int
+
+	// transformComplete is whether the transformation is complete,
+	// regardless of whether or not it was successful.
+	transformComplete bool
+}
+
+const defaultBufSize = 4096
+
+// NewReader returns a new Reader that wraps r by transforming the bytes read
+// via t. It calls Reset on t.
+func NewReader(r io.Reader, t Transformer) *Reader {
+	t.Reset()
+	return &Reader{
+		r:   r,
+		t:   t,
+		dst: make([]byte, defaultBufSize),
+		src: make([]byte, defaultBufSize),
+	}
+}
+
+// Read implements the io.Reader interface.
+func (r *Reader) Read(p []byte) (int, error) {
+	n, err := 0, error(nil)
+	for {
+		// Copy out any transformed bytes and return the final error if we are done.
+		if r.dst0 != r.dst1 {
+			n = copy(p, r.dst[r.dst0:r.dst1])
+			r.dst0 += n
+			if r.dst0 == r.dst1 && r.transformComplete {
+				return n, r.err
+			}
+			return n, nil
+		} else if r.transformComplete {
+			return 0, r.err
+		}
+
+		// Try to transform some source bytes, or to flush the transformer if we
+		// are out of source bytes. We do this even if r.r.Read returned an error.
+		// As the io.Reader documentation says, "process the n > 0 bytes returned
+		// before considering the error".
+		if r.src0 != r.src1 || r.err != nil {
+			r.dst0 = 0
+			r.dst1, n, err = r.t.Transform(r.dst, r.src[r.src0:r.src1], r.err == io.EOF)
+			r.src0 += n
+
+			switch {
+			case err == nil:
+				if r.src0 != r.src1 {
+					r.err = errInconsistentByteCount
+				}
+				// The Transform call was successful; we are complete if we
+				// cannot read more bytes into src.
+				r.transformComplete = r.err != nil
+				continue
+			case err == ErrShortDst && (r.dst1 != 0 || n != 0):
+				// Make room in dst by copying out, and try again.
+				continue
+			case err == ErrShortSrc && r.src1-r.src0 != len(r.src) && r.err == nil:
+				// Read more bytes into src via the code below, and try again.
+			default:
+				r.transformComplete = true
+				// The reader error (r.err) takes precedence over the
+				// transformer error (err) unless r.err is nil or io.EOF.
+				if r.err == nil || r.err == io.EOF {
+					r.err = err
+				}
+				continue
+			}
+		}
+
+		// Move any untransformed source bytes to the start of the buffer
+		// and read more bytes.
+		if r.src0 != 0 {
+			r.src0, r.src1 = 0, copy(r.src, r.src[r.src0:r.src1])
+		}
+		n, r.err = r.r.Read(r.src[r.src1:])
+		r.src1 += n
+	}
+}
+
+// TODO: implement ReadByte (and ReadRune??).
+
+// Writer wraps another io.Writer by transforming the bytes read.
+// The user needs to call Close to flush unwritten bytes that may
+// be buffered.
+type Writer struct {
+	w   io.Writer
+	t   Transformer
+	dst []byte
+
+	// src[:n] contains bytes that have not yet passed through t.
+	src []byte
+	n   int
+}
+
+// NewWriter returns a new Writer that wraps w by transforming the bytes written
+// via t. It calls Reset on t.
+func NewWriter(w io.Writer, t Transformer) *Writer {
+	t.Reset()
+	return &Writer{
+		w:   w,
+		t:   t,
+		dst: make([]byte, defaultBufSize),
+		src: make([]byte, defaultBufSize),
+	}
+}
+
+// Write implements the io.Writer interface. If there are not enough
+// bytes available to complete a Transform, the bytes will be buffered
+// for the next write. Call Close to convert the remaining bytes.
+func (w *Writer) Write(data []byte) (n int, err error) {
+	src := data
+	if w.n > 0 {
+		// Append bytes from data to the last remainder.
+		// TODO: limit the amount copied on first try.
+		n = copy(w.src[w.n:], data)
+		w.n += n
+		src = w.src[:w.n]
+	}
+	for {
+		nDst, nSrc, err := w.t.Transform(w.dst, src, false)
+		if _, werr := w.w.Write(w.dst[:nDst]); werr != nil {
+			return n, werr
+		}
+		src = src[nSrc:]
+		if w.n == 0 {
+			n += nSrc
+		} else if len(src) <= n {
+			// Enough bytes from w.src have been consumed. We make src point
+			// to data instead to reduce the copying.
+			w.n = 0
+			n -= len(src)
+			src = data[n:]
+			if n < len(data) && (err == nil || err == ErrShortSrc) {
+				continue
+			}
+		}
+		switch err {
+		case ErrShortDst:
+			// This error is okay as long as we are making progress.
+			if nDst > 0 || nSrc > 0 {
+				continue
+			}
+		case ErrShortSrc:
+			if len(src) < len(w.src) {
+				m := copy(w.src, src)
+				// If w.n > 0, bytes from data were already copied to w.src and n
+				// was already set to the number of bytes consumed.
+				if w.n == 0 {
+					n += m
+				}
+				w.n = m
+				err = nil
+			} else if nDst > 0 || nSrc > 0 {
+				// Not enough buffer to store the remainder. Keep processing as
+				// long as there is progress. Without this case, transforms that
+				// require a lookahead larger than the buffer may result in an
+				// error. This is not something one may expect to be common in
+				// practice, but it may occur when buffers are set to small
+				// sizes during testing.
+				continue
+			}
+		case nil:
+			if w.n > 0 {
+				err = errInconsistentByteCount
+			}
+		}
+		return n, err
+	}
+}
+
+// Close implements the io.Closer interface.
+func (w *Writer) Close() error {
+	src := w.src[:w.n]
+	for {
+		nDst, nSrc, err := w.t.Transform(w.dst, src, true)
+		if _, werr := w.w.Write(w.dst[:nDst]); werr != nil {
+			return werr
+		}
+		if err != ErrShortDst {
+			return err
+		}
+		src = src[nSrc:]
+	}
+}
+
+type nop struct{ NopResetter }
+
+func (nop) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+	n := copy(dst, src)
+	if n < len(src) {
+		err = ErrShortDst
+	}
+	return n, n, err
+}
+
+func (nop) Span(src []byte, atEOF bool) (n int, err error) {
+	return len(src), nil
+}
+
+type discard struct{ NopResetter }
+
+func (discard) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+	return 0, len(src), nil
+}
+
+var (
+	// Discard is a Transformer for which all Transform calls succeed
+	// by consuming all bytes and writing nothing.
+	Discard Transformer = discard{}
+
+	// Nop is a SpanningTransformer that copies src to dst.
+	Nop SpanningTransformer = nop{}
+)
+
+// chain is a sequence of links. A chain with N Transformers has N+1 links and
+// N+1 buffers. Of those N+1 buffers, the first and last are the src and dst
+// buffers given to chain.Transform and the middle N-1 buffers are intermediate
+// buffers owned by the chain. The i'th link transforms bytes from the i'th
+// buffer chain.link[i].b at read offset chain.link[i].p to the i+1'th buffer
+// chain.link[i+1].b at write offset chain.link[i+1].n, for i in [0, N).
+type chain struct {
+	link []link
+	err  error
+	// errStart is the index at which the error occurred plus 1. Processing
+	// errStart at this level at the next call to Transform. As long as
+	// errStart > 0, chain will not consume any more source bytes.
+	errStart int
+}
+
+func (c *chain) fatalError(errIndex int, err error) {
+	if i := errIndex + 1; i > c.errStart {
+		c.errStart = i
+		c.err = err
+	}
+}
+
+type link struct {
+	t Transformer
+	// b[p:n] holds the bytes to be transformed by t.
+	b []byte
+	p int
+	n int
+}
+
+func (l *link) src() []byte {
+	return l.b[l.p:l.n]
+}
+
+func (l *link) dst() []byte {
+	return l.b[l.n:]
+}
+
+// Chain returns a Transformer that applies t in sequence.
+func Chain(t ...Transformer) Transformer {
+	if len(t) == 0 {
+		return nop{}
+	}
+	c := &chain{link: make([]link, len(t)+1)}
+	for i, tt := range t {
+		c.link[i].t = tt
+	}
+	// Allocate intermediate buffers.
+	b := make([][defaultBufSize]byte, len(t)-1)
+	for i := range b {
+		c.link[i+1].b = b[i][:]
+	}
+	return c
+}
+
+// Reset resets the state of Chain. It calls Reset on all the Transformers.
+func (c *chain) Reset() {
+	for i, l := range c.link {
+		if l.t != nil {
+			l.t.Reset()
+		}
+		c.link[i].p, c.link[i].n = 0, 0
+	}
+}
+
+// TODO: make chain use Span (is going to be fun to implement!)
+
+// Transform applies the transformers of c in sequence.
+func (c *chain) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+	// Set up src and dst in the chain.
+	srcL := &c.link[0]
+	dstL := &c.link[len(c.link)-1]
+	srcL.b, srcL.p, srcL.n = src, 0, len(src)
+	dstL.b, dstL.n = dst, 0
+	var lastFull, needProgress bool // for detecting progress
+
+	// i is the index of the next Transformer to apply, for i in [low, high].
+	// low is the lowest index for which c.link[low] may still produce bytes.
+	// high is the highest index for which c.link[high] has a Transformer.
+	// The error returned by Transform determines whether to increase or
+	// decrease i. We try to completely fill a buffer before converting it.
+	for low, i, high := c.errStart, c.errStart, len(c.link)-2; low <= i && i <= high; {
+		in, out := &c.link[i], &c.link[i+1]
+		nDst, nSrc, err0 := in.t.Transform(out.dst(), in.src(), atEOF && low == i)
+		out.n += nDst
+		in.p += nSrc
+		if i > 0 && in.p == in.n {
+			in.p, in.n = 0, 0
+		}
+		needProgress, lastFull = lastFull, false
+		switch err0 {
+		case ErrShortDst:
+			// Process the destination buffer next. Return if we are already
+			// at the high index.
+			if i == high {
+				return dstL.n, srcL.p, ErrShortDst
+			}
+			if out.n != 0 {
+				i++
+				// If the Transformer at the next index is not able to process any
+				// source bytes there is nothing that can be done to make progress
+				// and the bytes will remain unprocessed. lastFull is used to
+				// detect this and break out of the loop with a fatal error.
+				lastFull = true
+				continue
+			}
+			// The destination buffer was too small, but is completely empty.
+			// Return a fatal error as this transformation can never complete.
+			c.fatalError(i, errShortInternal)
+		case ErrShortSrc:
+			if i == 0 {
+				// Save ErrShortSrc in err. All other errors take precedence.
+				err = ErrShortSrc
+				break
+			}
+			// Source bytes were depleted before filling up the destination buffer.
+			// Verify we made some progress, move the remaining bytes to the errStart
+			// and try to get more source bytes.
+			if needProgress && nSrc == 0 || in.n-in.p == len(in.b) {
+				// There were not enough source bytes to proceed while the source
+				// buffer cannot hold any more bytes. Return a fatal error as this
+				// transformation can never complete.
+				c.fatalError(i, errShortInternal)
+				break
+			}
+			// in.b is an internal buffer and we can make progress.
+			in.p, in.n = 0, copy(in.b, in.src())
+			fallthrough
+		case nil:
+			// if i == low, we have depleted the bytes at index i or any lower levels.
+			// In that case we increase low and i. In all other cases we decrease i to
+			// fetch more bytes before proceeding to the next index.
+			if i > low {
+				i--
+				continue
+			}
+		default:
+			c.fatalError(i, err0)
+		}
+		// Exhausted level low or fatal error: increase low and continue
+		// to process the bytes accepted so far.
+		i++
+		low = i
+	}
+
+	// If c.errStart > 0, this means we found a fatal error.  We will clear
+	// all upstream buffers. At this point, no more progress can be made
+	// downstream, as Transform would have bailed while handling ErrShortDst.
+	if c.errStart > 0 {
+		for i := 1; i < c.errStart; i++ {
+			c.link[i].p, c.link[i].n = 0, 0
+		}
+		err, c.errStart, c.err = c.err, 0, nil
+	}
+	return dstL.n, srcL.p, err
+}
+
+// Deprecated: use runes.Remove instead.
+func RemoveFunc(f func(r rune) bool) Transformer {
+	return removeF(f)
+}
+
+type removeF func(r rune) bool
+
+func (removeF) Reset() {}
+
+// Transform implements the Transformer interface.
+func (t removeF) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+	for r, sz := rune(0), 0; len(src) > 0; src = src[sz:] {
+
+		if r = rune(src[0]); r < utf8.RuneSelf {
+			sz = 1
+		} else {
+			r, sz = utf8.DecodeRune(src)
+
+			if sz == 1 {
+				// Invalid rune.
+				if !atEOF && !utf8.FullRune(src) {
+					err = ErrShortSrc
+					break
+				}
+				// We replace illegal bytes with RuneError. Not doing so might
+				// otherwise turn a sequence of invalid UTF-8 into valid UTF-8.
+				// The resulting byte sequence may subsequently contain runes
+				// for which t(r) is true that were passed unnoticed.
+				if !t(r) {
+					if nDst+3 > len(dst) {
+						err = ErrShortDst
+						break
+					}
+					nDst += copy(dst[nDst:], "\uFFFD")
+				}
+				nSrc++
+				continue
+			}
+		}
+
+		if !t(r) {
+			if nDst+sz > len(dst) {
+				err = ErrShortDst
+				break
+			}
+			nDst += copy(dst[nDst:], src[:sz])
+		}
+		nSrc += sz
+	}
+	return
+}
+
+// grow returns a new []byte that is longer than b, and copies the first n bytes
+// of b to the start of the new slice.
+func grow(b []byte, n int) []byte {
+	m := len(b)
+	if m <= 32 {
+		m = 64
+	} else if m <= 256 {
+		m *= 2
+	} else {
+		m += m >> 1
+	}
+	buf := make([]byte, m)
+	copy(buf, b[:n])
+	return buf
+}
+
+const initialBufSize = 128
+
+// String returns a string with the result of converting s[:n] using t, where
+// n <= len(s). If err == nil, n will be len(s). It calls Reset on t.
+func String(t Transformer, s string) (result string, n int, err error) {
+	t.Reset()
+	if s == "" {
+		// Fast path for the common case for empty input. Results in about a
+		// 86% reduction of running time for BenchmarkStringLowerEmpty.
+		if _, _, err := t.Transform(nil, nil, true); err == nil {
+			return "", 0, nil
+		}
+	}
+
+	// Allocate only once. Note that both dst and src escape when passed to
+	// Transform.
+	buf := [2 * initialBufSize]byte{}
+	dst := buf[:initialBufSize:initialBufSize]
+	src := buf[initialBufSize : 2*initialBufSize]
+
+	// The input string s is transformed in multiple chunks (starting with a
+	// chunk size of initialBufSize). nDst and nSrc are per-chunk (or
+	// per-Transform-call) indexes, pDst and pSrc are overall indexes.
+	nDst, nSrc := 0, 0
+	pDst, pSrc := 0, 0
+
+	// pPrefix is the length of a common prefix: the first pPrefix bytes of the
+	// result will equal the first pPrefix bytes of s. It is not guaranteed to
+	// be the largest such value, but if pPrefix, len(result) and len(s) are
+	// all equal after the final transform (i.e. calling Transform with atEOF
+	// being true returned nil error) then we don't need to allocate a new
+	// result string.
+	pPrefix := 0
+	for {
+		// Invariant: pDst == pPrefix && pSrc == pPrefix.
+
+		n := copy(src, s[pSrc:])
+		nDst, nSrc, err = t.Transform(dst, src[:n], pSrc+n == len(s))
+		pDst += nDst
+		pSrc += nSrc
+
+		// TODO:  let transformers implement an optional Spanner interface, akin
+		// to norm's QuickSpan. This would even allow us to avoid any allocation.
+		if !bytes.Equal(dst[:nDst], src[:nSrc]) {
+			break
+		}
+		pPrefix = pSrc
+		if err == ErrShortDst {
+			// A buffer can only be short if a transformer modifies its input.
+			break
+		} else if err == ErrShortSrc {
+			if nSrc == 0 {
+				// No progress was made.
+				break
+			}
+			// Equal so far and !atEOF, so continue checking.
+		} else if err != nil || pPrefix == len(s) {
+			return string(s[:pPrefix]), pPrefix, err
+		}
+	}
+	// Post-condition: pDst == pPrefix + nDst && pSrc == pPrefix + nSrc.
+
+	// We have transformed the first pSrc bytes of the input s to become pDst
+	// transformed bytes. Those transformed bytes are discontiguous: the first
+	// pPrefix of them equal s[:pPrefix] and the last nDst of them equal
+	// dst[:nDst]. We copy them around, into a new dst buffer if necessary, so
+	// that they become one contiguous slice: dst[:pDst].
+	if pPrefix != 0 {
+		newDst := dst
+		if pDst > len(newDst) {
+			newDst = make([]byte, len(s)+nDst-nSrc)
+		}
+		copy(newDst[pPrefix:pDst], dst[:nDst])
+		copy(newDst[:pPrefix], s[:pPrefix])
+		dst = newDst
+	}
+
+	// Prevent duplicate Transform calls with atEOF being true at the end of
+	// the input. Also return if we have an unrecoverable error.
+	if (err == nil && pSrc == len(s)) ||
+		(err != nil && err != ErrShortDst && err != ErrShortSrc) {
+		return string(dst[:pDst]), pSrc, err
+	}
+
+	// Transform the remaining input, growing dst and src buffers as necessary.
+	for {
+		n := copy(src, s[pSrc:])
+		nDst, nSrc, err := t.Transform(dst[pDst:], src[:n], pSrc+n == len(s))
+		pDst += nDst
+		pSrc += nSrc
+
+		// If we got ErrShortDst or ErrShortSrc, do not grow as long as we can
+		// make progress. This may avoid excessive allocations.
+		if err == ErrShortDst {
+			if nDst == 0 {
+				dst = grow(dst, pDst)
+			}
+		} else if err == ErrShortSrc {
+			if nSrc == 0 {
+				src = grow(src, 0)
+			}
+		} else if err != nil || pSrc == len(s) {
+			return string(dst[:pDst]), pSrc, err
+		}
+	}
+}
+
+// Bytes returns a new byte slice with the result of converting b[:n] using t,
+// where n <= len(b). If err == nil, n will be len(b). It calls Reset on t.
+func Bytes(t Transformer, b []byte) (result []byte, n int, err error) {
+	return doAppend(t, 0, make([]byte, len(b)), b)
+}
+
+// Append appends the result of converting src[:n] using t to dst, where
+// n <= len(src), If err == nil, n will be len(src). It calls Reset on t.
+func Append(t Transformer, dst, src []byte) (result []byte, n int, err error) {
+	if len(dst) == cap(dst) {
+		n := len(src) + len(dst) // It is okay for this to be 0.
+		b := make([]byte, n)
+		dst = b[:copy(b, dst)]
+	}
+	return doAppend(t, len(dst), dst[:cap(dst)], src)
+}
+
+func doAppend(t Transformer, pDst int, dst, src []byte) (result []byte, n int, err error) {
+	t.Reset()
+	pSrc := 0
+	for {
+		nDst, nSrc, err := t.Transform(dst[pDst:], src[pSrc:], true)
+		pDst += nDst
+		pSrc += nSrc
+		if err != ErrShortDst {
+			return dst[:pDst], pSrc, err
+		}
+
+		// Grow the destination buffer, but do not grow as long as we can make
+		// progress. This may avoid excessive allocations.
+		if nDst == 0 {
+			dst = grow(dst, pDst)
+		}
+	}
+}