diff --git a/vendor/github.com/coreos/go-semver/semver/semver.go b/vendor/github.com/coreos/go-semver/semver/semver.go
new file mode 100644
index 0000000..76cf485
--- /dev/null
+++ b/vendor/github.com/coreos/go-semver/semver/semver.go
@@ -0,0 +1,296 @@
+// Copyright 2013-2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Semantic Versions http://semver.org
+package semver
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+type Version struct {
+	Major      int64
+	Minor      int64
+	Patch      int64
+	PreRelease PreRelease
+	Metadata   string
+}
+
+type PreRelease string
+
+func splitOff(input *string, delim string) (val string) {
+	parts := strings.SplitN(*input, delim, 2)
+
+	if len(parts) == 2 {
+		*input = parts[0]
+		val = parts[1]
+	}
+
+	return val
+}
+
+func New(version string) *Version {
+	return Must(NewVersion(version))
+}
+
+func NewVersion(version string) (*Version, error) {
+	v := Version{}
+
+	if err := v.Set(version); err != nil {
+		return nil, err
+	}
+
+	return &v, nil
+}
+
+// Must is a helper for wrapping NewVersion and will panic if err is not nil.
+func Must(v *Version, err error) *Version {
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// Set parses and updates v from the given version string. Implements flag.Value
+func (v *Version) Set(version string) error {
+	metadata := splitOff(&version, "+")
+	preRelease := PreRelease(splitOff(&version, "-"))
+	dotParts := strings.SplitN(version, ".", 3)
+
+	if len(dotParts) != 3 {
+		return fmt.Errorf("%s is not in dotted-tri format", version)
+	}
+
+	if err := validateIdentifier(string(preRelease)); err != nil {
+		return fmt.Errorf("failed to validate pre-release: %v", err)
+	}
+
+	if err := validateIdentifier(metadata); err != nil {
+		return fmt.Errorf("failed to validate metadata: %v", err)
+	}
+
+	parsed := make([]int64, 3, 3)
+
+	for i, v := range dotParts[:3] {
+		val, err := strconv.ParseInt(v, 10, 64)
+		parsed[i] = val
+		if err != nil {
+			return err
+		}
+	}
+
+	v.Metadata = metadata
+	v.PreRelease = preRelease
+	v.Major = parsed[0]
+	v.Minor = parsed[1]
+	v.Patch = parsed[2]
+	return nil
+}
+
+func (v Version) String() string {
+	var buffer bytes.Buffer
+
+	fmt.Fprintf(&buffer, "%d.%d.%d", v.Major, v.Minor, v.Patch)
+
+	if v.PreRelease != "" {
+		fmt.Fprintf(&buffer, "-%s", v.PreRelease)
+	}
+
+	if v.Metadata != "" {
+		fmt.Fprintf(&buffer, "+%s", v.Metadata)
+	}
+
+	return buffer.String()
+}
+
+func (v *Version) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var data string
+	if err := unmarshal(&data); err != nil {
+		return err
+	}
+	return v.Set(data)
+}
+
+func (v Version) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + v.String() + `"`), nil
+}
+
+func (v *Version) UnmarshalJSON(data []byte) error {
+	l := len(data)
+	if l == 0 || string(data) == `""` {
+		return nil
+	}
+	if l < 2 || data[0] != '"' || data[l-1] != '"' {
+		return errors.New("invalid semver string")
+	}
+	return v.Set(string(data[1 : l-1]))
+}
+
+// Compare tests if v is less than, equal to, or greater than versionB,
+// returning -1, 0, or +1 respectively.
+func (v Version) Compare(versionB Version) int {
+	if cmp := recursiveCompare(v.Slice(), versionB.Slice()); cmp != 0 {
+		return cmp
+	}
+	return preReleaseCompare(v, versionB)
+}
+
+// Equal tests if v is equal to versionB.
+func (v Version) Equal(versionB Version) bool {
+	return v.Compare(versionB) == 0
+}
+
+// LessThan tests if v is less than versionB.
+func (v Version) LessThan(versionB Version) bool {
+	return v.Compare(versionB) < 0
+}
+
+// Slice converts the comparable parts of the semver into a slice of integers.
+func (v Version) Slice() []int64 {
+	return []int64{v.Major, v.Minor, v.Patch}
+}
+
+func (p PreRelease) Slice() []string {
+	preRelease := string(p)
+	return strings.Split(preRelease, ".")
+}
+
+func preReleaseCompare(versionA Version, versionB Version) int {
+	a := versionA.PreRelease
+	b := versionB.PreRelease
+
+	/* Handle the case where if two versions are otherwise equal it is the
+	 * one without a PreRelease that is greater */
+	if len(a) == 0 && (len(b) > 0) {
+		return 1
+	} else if len(b) == 0 && (len(a) > 0) {
+		return -1
+	}
+
+	// If there is a prerelease, check and compare each part.
+	return recursivePreReleaseCompare(a.Slice(), b.Slice())
+}
+
+func recursiveCompare(versionA []int64, versionB []int64) int {
+	if len(versionA) == 0 {
+		return 0
+	}
+
+	a := versionA[0]
+	b := versionB[0]
+
+	if a > b {
+		return 1
+	} else if a < b {
+		return -1
+	}
+
+	return recursiveCompare(versionA[1:], versionB[1:])
+}
+
+func recursivePreReleaseCompare(versionA []string, versionB []string) int {
+	// A larger set of pre-release fields has a higher precedence than a smaller set,
+	// if all of the preceding identifiers are equal.
+	if len(versionA) == 0 {
+		if len(versionB) > 0 {
+			return -1
+		}
+		return 0
+	} else if len(versionB) == 0 {
+		// We're longer than versionB so return 1.
+		return 1
+	}
+
+	a := versionA[0]
+	b := versionB[0]
+
+	aInt := false
+	bInt := false
+
+	aI, err := strconv.Atoi(versionA[0])
+	if err == nil {
+		aInt = true
+	}
+
+	bI, err := strconv.Atoi(versionB[0])
+	if err == nil {
+		bInt = true
+	}
+
+	// Numeric identifiers always have lower precedence than non-numeric identifiers.
+	if aInt && !bInt {
+		return -1
+	} else if !aInt && bInt {
+		return 1
+	}
+
+	// Handle Integer Comparison
+	if aInt && bInt {
+		if aI > bI {
+			return 1
+		} else if aI < bI {
+			return -1
+		}
+	}
+
+	// Handle String Comparison
+	if a > b {
+		return 1
+	} else if a < b {
+		return -1
+	}
+
+	return recursivePreReleaseCompare(versionA[1:], versionB[1:])
+}
+
+// BumpMajor increments the Major field by 1 and resets all other fields to their default values
+func (v *Version) BumpMajor() {
+	v.Major += 1
+	v.Minor = 0
+	v.Patch = 0
+	v.PreRelease = PreRelease("")
+	v.Metadata = ""
+}
+
+// BumpMinor increments the Minor field by 1 and resets all other fields to their default values
+func (v *Version) BumpMinor() {
+	v.Minor += 1
+	v.Patch = 0
+	v.PreRelease = PreRelease("")
+	v.Metadata = ""
+}
+
+// BumpPatch increments the Patch field by 1 and resets all other fields to their default values
+func (v *Version) BumpPatch() {
+	v.Patch += 1
+	v.PreRelease = PreRelease("")
+	v.Metadata = ""
+}
+
+// validateIdentifier makes sure the provided identifier satisfies semver spec
+func validateIdentifier(id string) error {
+	if id != "" && !reIdentifier.MatchString(id) {
+		return fmt.Errorf("%s is not a valid semver identifier", id)
+	}
+	return nil
+}
+
+// reIdentifier is a regular expression used to check that pre-release and metadata
+// identifiers satisfy the spec requirements
+var reIdentifier = regexp.MustCompile(`^[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*$`)