diff --git a/vendor/google.golang.org/appengine/urlfetch/urlfetch.go b/vendor/google.golang.org/appengine/urlfetch/urlfetch.go
new file mode 100644
index 0000000..6ffe1e6
--- /dev/null
+++ b/vendor/google.golang.org/appengine/urlfetch/urlfetch.go
@@ -0,0 +1,210 @@
+// Copyright 2011 Google Inc. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+// Package urlfetch provides an http.RoundTripper implementation
+// for fetching URLs via App Engine's urlfetch service.
+package urlfetch // import "google.golang.org/appengine/urlfetch"
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"golang.org/x/net/context"
+
+	"google.golang.org/appengine/internal"
+	pb "google.golang.org/appengine/internal/urlfetch"
+)
+
+// Transport is an implementation of http.RoundTripper for
+// App Engine. Users should generally create an http.Client using
+// this transport and use the Client rather than using this transport
+// directly.
+type Transport struct {
+	Context context.Context
+
+	// Controls whether the application checks the validity of SSL certificates
+	// over HTTPS connections. A value of false (the default) instructs the
+	// application to send a request to the server only if the certificate is
+	// valid and signed by a trusted certificate authority (CA), and also
+	// includes a hostname that matches the certificate. A value of true
+	// instructs the application to perform no certificate validation.
+	AllowInvalidServerCertificate bool
+}
+
+// Verify statically that *Transport implements http.RoundTripper.
+var _ http.RoundTripper = (*Transport)(nil)
+
+// Client returns an *http.Client using a default urlfetch Transport. This
+// client will have the default deadline of 5 seconds, and will check the
+// validity of SSL certificates.
+//
+// Any deadline of the provided context will be used for requests through this client;
+// if the client does not have a deadline then a 5 second default is used.
+func Client(ctx context.Context) *http.Client {
+	return &http.Client{
+		Transport: &Transport{
+			Context: ctx,
+		},
+	}
+}
+
+type bodyReader struct {
+	content   []byte
+	truncated bool
+	closed    bool
+}
+
+// ErrTruncatedBody is the error returned after the final Read() from a
+// response's Body if the body has been truncated by App Engine's proxy.
+var ErrTruncatedBody = errors.New("urlfetch: truncated body")
+
+func statusCodeToText(code int) string {
+	if t := http.StatusText(code); t != "" {
+		return t
+	}
+	return strconv.Itoa(code)
+}
+
+func (br *bodyReader) Read(p []byte) (n int, err error) {
+	if br.closed {
+		if br.truncated {
+			return 0, ErrTruncatedBody
+		}
+		return 0, io.EOF
+	}
+	n = copy(p, br.content)
+	if n > 0 {
+		br.content = br.content[n:]
+		return
+	}
+	if br.truncated {
+		br.closed = true
+		return 0, ErrTruncatedBody
+	}
+	return 0, io.EOF
+}
+
+func (br *bodyReader) Close() error {
+	br.closed = true
+	br.content = nil
+	return nil
+}
+
+// A map of the URL Fetch-accepted methods that take a request body.
+var methodAcceptsRequestBody = map[string]bool{
+	"POST":  true,
+	"PUT":   true,
+	"PATCH": true,
+}
+
+// urlString returns a valid string given a URL. This function is necessary because
+// the String method of URL doesn't correctly handle URLs with non-empty Opaque values.
+// See http://code.google.com/p/go/issues/detail?id=4860.
+func urlString(u *url.URL) string {
+	if u.Opaque == "" || strings.HasPrefix(u.Opaque, "//") {
+		return u.String()
+	}
+	aux := *u
+	aux.Opaque = "//" + aux.Host + aux.Opaque
+	return aux.String()
+}
+
+// RoundTrip issues a single HTTP request and returns its response. Per the
+// http.RoundTripper interface, RoundTrip only returns an error if there
+// was an unsupported request or the URL Fetch proxy fails.
+// Note that HTTP response codes such as 5xx, 403, 404, etc are not
+// errors as far as the transport is concerned and will be returned
+// with err set to nil.
+func (t *Transport) RoundTrip(req *http.Request) (res *http.Response, err error) {
+	methNum, ok := pb.URLFetchRequest_RequestMethod_value[req.Method]
+	if !ok {
+		return nil, fmt.Errorf("urlfetch: unsupported HTTP method %q", req.Method)
+	}
+
+	method := pb.URLFetchRequest_RequestMethod(methNum)
+
+	freq := &pb.URLFetchRequest{
+		Method:                        &method,
+		Url:                           proto.String(urlString(req.URL)),
+		FollowRedirects:               proto.Bool(false), // http.Client's responsibility
+		MustValidateServerCertificate: proto.Bool(!t.AllowInvalidServerCertificate),
+	}
+	if deadline, ok := t.Context.Deadline(); ok {
+		freq.Deadline = proto.Float64(deadline.Sub(time.Now()).Seconds())
+	}
+
+	for k, vals := range req.Header {
+		for _, val := range vals {
+			freq.Header = append(freq.Header, &pb.URLFetchRequest_Header{
+				Key:   proto.String(k),
+				Value: proto.String(val),
+			})
+		}
+	}
+	if methodAcceptsRequestBody[req.Method] && req.Body != nil {
+		// Avoid a []byte copy if req.Body has a Bytes method.
+		switch b := req.Body.(type) {
+		case interface {
+			Bytes() []byte
+		}:
+			freq.Payload = b.Bytes()
+		default:
+			freq.Payload, err = ioutil.ReadAll(req.Body)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	fres := &pb.URLFetchResponse{}
+	if err := internal.Call(t.Context, "urlfetch", "Fetch", freq, fres); err != nil {
+		return nil, err
+	}
+
+	res = &http.Response{}
+	res.StatusCode = int(*fres.StatusCode)
+	res.Status = fmt.Sprintf("%d %s", res.StatusCode, statusCodeToText(res.StatusCode))
+	res.Header = make(http.Header)
+	res.Request = req
+
+	// Faked:
+	res.ProtoMajor = 1
+	res.ProtoMinor = 1
+	res.Proto = "HTTP/1.1"
+	res.Close = true
+
+	for _, h := range fres.Header {
+		hkey := http.CanonicalHeaderKey(*h.Key)
+		hval := *h.Value
+		if hkey == "Content-Length" {
+			// Will get filled in below for all but HEAD requests.
+			if req.Method == "HEAD" {
+				res.ContentLength, _ = strconv.ParseInt(hval, 10, 64)
+			}
+			continue
+		}
+		res.Header.Add(hkey, hval)
+	}
+
+	if req.Method != "HEAD" {
+		res.ContentLength = int64(len(fres.Content))
+	}
+
+	truncated := fres.GetContentWasTruncated()
+	res.Body = &bodyReader{content: fres.Content, truncated: truncated}
+	return
+}
+
+func init() {
+	internal.RegisterErrorCodeMap("urlfetch", pb.URLFetchServiceError_ErrorCode_name)
+	internal.RegisterTimeoutErrorCode("urlfetch", int32(pb.URLFetchServiceError_DEADLINE_EXCEEDED))
+}