diff --git a/vendor/gopkg.in/yaml.v2/encode.go b/vendor/gopkg.in/yaml.v2/encode.go
new file mode 100644
index 0000000..0ee738e
--- /dev/null
+++ b/vendor/gopkg.in/yaml.v2/encode.go
@@ -0,0 +1,390 @@
+package yaml
+
+import (
+	"encoding"
+	"fmt"
+	"io"
+	"reflect"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+	"unicode/utf8"
+)
+
+// jsonNumber is the interface of the encoding/json.Number datatype.
+// Repeating the interface here avoids a dependency on encoding/json, and also
+// supports other libraries like jsoniter, which use a similar datatype with
+// the same interface. Detecting this interface is useful when dealing with
+// structures containing json.Number, which is a string under the hood. The
+// encoder should prefer the use of Int64(), Float64() and string(), in that
+// order, when encoding this type.
+type jsonNumber interface {
+	Float64() (float64, error)
+	Int64() (int64, error)
+	String() string
+}
+
+type encoder struct {
+	emitter yaml_emitter_t
+	event   yaml_event_t
+	out     []byte
+	flow    bool
+	// doneInit holds whether the initial stream_start_event has been
+	// emitted.
+	doneInit bool
+}
+
+func newEncoder() *encoder {
+	e := &encoder{}
+	yaml_emitter_initialize(&e.emitter)
+	yaml_emitter_set_output_string(&e.emitter, &e.out)
+	yaml_emitter_set_unicode(&e.emitter, true)
+	return e
+}
+
+func newEncoderWithWriter(w io.Writer) *encoder {
+	e := &encoder{}
+	yaml_emitter_initialize(&e.emitter)
+	yaml_emitter_set_output_writer(&e.emitter, w)
+	yaml_emitter_set_unicode(&e.emitter, true)
+	return e
+}
+
+func (e *encoder) init() {
+	if e.doneInit {
+		return
+	}
+	yaml_stream_start_event_initialize(&e.event, yaml_UTF8_ENCODING)
+	e.emit()
+	e.doneInit = true
+}
+
+func (e *encoder) finish() {
+	e.emitter.open_ended = false
+	yaml_stream_end_event_initialize(&e.event)
+	e.emit()
+}
+
+func (e *encoder) destroy() {
+	yaml_emitter_delete(&e.emitter)
+}
+
+func (e *encoder) emit() {
+	// This will internally delete the e.event value.
+	e.must(yaml_emitter_emit(&e.emitter, &e.event))
+}
+
+func (e *encoder) must(ok bool) {
+	if !ok {
+		msg := e.emitter.problem
+		if msg == "" {
+			msg = "unknown problem generating YAML content"
+		}
+		failf("%s", msg)
+	}
+}
+
+func (e *encoder) marshalDoc(tag string, in reflect.Value) {
+	e.init()
+	yaml_document_start_event_initialize(&e.event, nil, nil, true)
+	e.emit()
+	e.marshal(tag, in)
+	yaml_document_end_event_initialize(&e.event, true)
+	e.emit()
+}
+
+func (e *encoder) marshal(tag string, in reflect.Value) {
+	if !in.IsValid() || in.Kind() == reflect.Ptr && in.IsNil() {
+		e.nilv()
+		return
+	}
+	iface := in.Interface()
+	switch m := iface.(type) {
+	case jsonNumber:
+		integer, err := m.Int64()
+		if err == nil {
+			// In this case the json.Number is a valid int64
+			in = reflect.ValueOf(integer)
+			break
+		}
+		float, err := m.Float64()
+		if err == nil {
+			// In this case the json.Number is a valid float64
+			in = reflect.ValueOf(float)
+			break
+		}
+		// fallback case - no number could be obtained
+		in = reflect.ValueOf(m.String())
+	case time.Time, *time.Time:
+		// Although time.Time implements TextMarshaler,
+		// we don't want to treat it as a string for YAML
+		// purposes because YAML has special support for
+		// timestamps.
+	case Marshaler:
+		v, err := m.MarshalYAML()
+		if err != nil {
+			fail(err)
+		}
+		if v == nil {
+			e.nilv()
+			return
+		}
+		in = reflect.ValueOf(v)
+	case encoding.TextMarshaler:
+		text, err := m.MarshalText()
+		if err != nil {
+			fail(err)
+		}
+		in = reflect.ValueOf(string(text))
+	case nil:
+		e.nilv()
+		return
+	}
+	switch in.Kind() {
+	case reflect.Interface:
+		e.marshal(tag, in.Elem())
+	case reflect.Map:
+		e.mapv(tag, in)
+	case reflect.Ptr:
+		if in.Type() == ptrTimeType {
+			e.timev(tag, in.Elem())
+		} else {
+			e.marshal(tag, in.Elem())
+		}
+	case reflect.Struct:
+		if in.Type() == timeType {
+			e.timev(tag, in)
+		} else {
+			e.structv(tag, in)
+		}
+	case reflect.Slice, reflect.Array:
+		if in.Type().Elem() == mapItemType {
+			e.itemsv(tag, in)
+		} else {
+			e.slicev(tag, in)
+		}
+	case reflect.String:
+		e.stringv(tag, in)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		if in.Type() == durationType {
+			e.stringv(tag, reflect.ValueOf(iface.(time.Duration).String()))
+		} else {
+			e.intv(tag, in)
+		}
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		e.uintv(tag, in)
+	case reflect.Float32, reflect.Float64:
+		e.floatv(tag, in)
+	case reflect.Bool:
+		e.boolv(tag, in)
+	default:
+		panic("cannot marshal type: " + in.Type().String())
+	}
+}
+
+func (e *encoder) mapv(tag string, in reflect.Value) {
+	e.mappingv(tag, func() {
+		keys := keyList(in.MapKeys())
+		sort.Sort(keys)
+		for _, k := range keys {
+			e.marshal("", k)
+			e.marshal("", in.MapIndex(k))
+		}
+	})
+}
+
+func (e *encoder) itemsv(tag string, in reflect.Value) {
+	e.mappingv(tag, func() {
+		slice := in.Convert(reflect.TypeOf([]MapItem{})).Interface().([]MapItem)
+		for _, item := range slice {
+			e.marshal("", reflect.ValueOf(item.Key))
+			e.marshal("", reflect.ValueOf(item.Value))
+		}
+	})
+}
+
+func (e *encoder) structv(tag string, in reflect.Value) {
+	sinfo, err := getStructInfo(in.Type())
+	if err != nil {
+		panic(err)
+	}
+	e.mappingv(tag, func() {
+		for _, info := range sinfo.FieldsList {
+			var value reflect.Value
+			if info.Inline == nil {
+				value = in.Field(info.Num)
+			} else {
+				value = in.FieldByIndex(info.Inline)
+			}
+			if info.OmitEmpty && isZero(value) {
+				continue
+			}
+			e.marshal("", reflect.ValueOf(info.Key))
+			e.flow = info.Flow
+			e.marshal("", value)
+		}
+		if sinfo.InlineMap >= 0 {
+			m := in.Field(sinfo.InlineMap)
+			if m.Len() > 0 {
+				e.flow = false
+				keys := keyList(m.MapKeys())
+				sort.Sort(keys)
+				for _, k := range keys {
+					if _, found := sinfo.FieldsMap[k.String()]; found {
+						panic(fmt.Sprintf("Can't have key %q in inlined map; conflicts with struct field", k.String()))
+					}
+					e.marshal("", k)
+					e.flow = false
+					e.marshal("", m.MapIndex(k))
+				}
+			}
+		}
+	})
+}
+
+func (e *encoder) mappingv(tag string, f func()) {
+	implicit := tag == ""
+	style := yaml_BLOCK_MAPPING_STYLE
+	if e.flow {
+		e.flow = false
+		style = yaml_FLOW_MAPPING_STYLE
+	}
+	yaml_mapping_start_event_initialize(&e.event, nil, []byte(tag), implicit, style)
+	e.emit()
+	f()
+	yaml_mapping_end_event_initialize(&e.event)
+	e.emit()
+}
+
+func (e *encoder) slicev(tag string, in reflect.Value) {
+	implicit := tag == ""
+	style := yaml_BLOCK_SEQUENCE_STYLE
+	if e.flow {
+		e.flow = false
+		style = yaml_FLOW_SEQUENCE_STYLE
+	}
+	e.must(yaml_sequence_start_event_initialize(&e.event, nil, []byte(tag), implicit, style))
+	e.emit()
+	n := in.Len()
+	for i := 0; i < n; i++ {
+		e.marshal("", in.Index(i))
+	}
+	e.must(yaml_sequence_end_event_initialize(&e.event))
+	e.emit()
+}
+
+// isBase60 returns whether s is in base 60 notation as defined in YAML 1.1.
+//
+// The base 60 float notation in YAML 1.1 is a terrible idea and is unsupported
+// in YAML 1.2 and by this package, but these should be marshalled quoted for
+// the time being for compatibility with other parsers.
+func isBase60Float(s string) (result bool) {
+	// Fast path.
+	if s == "" {
+		return false
+	}
+	c := s[0]
+	if !(c == '+' || c == '-' || c >= '0' && c <= '9') || strings.IndexByte(s, ':') < 0 {
+		return false
+	}
+	// Do the full match.
+	return base60float.MatchString(s)
+}
+
+// From http://yaml.org/type/float.html, except the regular expression there
+// is bogus. In practice parsers do not enforce the "\.[0-9_]*" suffix.
+var base60float = regexp.MustCompile(`^[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+(?:\.[0-9_]*)?$`)
+
+func (e *encoder) stringv(tag string, in reflect.Value) {
+	var style yaml_scalar_style_t
+	s := in.String()
+	canUsePlain := true
+	switch {
+	case !utf8.ValidString(s):
+		if tag == yaml_BINARY_TAG {
+			failf("explicitly tagged !!binary data must be base64-encoded")
+		}
+		if tag != "" {
+			failf("cannot marshal invalid UTF-8 data as %s", shortTag(tag))
+		}
+		// It can't be encoded directly as YAML so use a binary tag
+		// and encode it as base64.
+		tag = yaml_BINARY_TAG
+		s = encodeBase64(s)
+	case tag == "":
+		// Check to see if it would resolve to a specific
+		// tag when encoded unquoted. If it doesn't,
+		// there's no need to quote it.
+		rtag, _ := resolve("", s)
+		canUsePlain = rtag == yaml_STR_TAG && !isBase60Float(s)
+	}
+	// Note: it's possible for user code to emit invalid YAML
+	// if they explicitly specify a tag and a string containing
+	// text that's incompatible with that tag.
+	switch {
+	case strings.Contains(s, "\n"):
+		style = yaml_LITERAL_SCALAR_STYLE
+	case canUsePlain:
+		style = yaml_PLAIN_SCALAR_STYLE
+	default:
+		style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+	}
+	e.emitScalar(s, "", tag, style)
+}
+
+func (e *encoder) boolv(tag string, in reflect.Value) {
+	var s string
+	if in.Bool() {
+		s = "true"
+	} else {
+		s = "false"
+	}
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) intv(tag string, in reflect.Value) {
+	s := strconv.FormatInt(in.Int(), 10)
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) uintv(tag string, in reflect.Value) {
+	s := strconv.FormatUint(in.Uint(), 10)
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) timev(tag string, in reflect.Value) {
+	t := in.Interface().(time.Time)
+	s := t.Format(time.RFC3339Nano)
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) floatv(tag string, in reflect.Value) {
+	// Issue #352: When formatting, use the precision of the underlying value
+	precision := 64
+	if in.Kind() == reflect.Float32 {
+		precision = 32
+	}
+
+	s := strconv.FormatFloat(in.Float(), 'g', -1, precision)
+	switch s {
+	case "+Inf":
+		s = ".inf"
+	case "-Inf":
+		s = "-.inf"
+	case "NaN":
+		s = ".nan"
+	}
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) nilv() {
+	e.emitScalar("null", "", "", yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) emitScalar(value, anchor, tag string, style yaml_scalar_style_t) {
+	implicit := tag == ""
+	e.must(yaml_scalar_event_initialize(&e.event, []byte(anchor), []byte(tag), []byte(value), implicit, implicit, style))
+	e.emit()
+}