Update deps without licenses

The following packes did not have discernible LICENSE files at the hash we have
vendored:
  github.com/beorn7/perks
  github.com/daviddengcn/go-colortext
  github.com/garyburd/redigo
  github.com/prometheus/common
  github.com/shurcooL/sanitized_anchor_name
  github.com/stretchr/objx

This commit updates all of them and updates the central LICENSE file.

vendor/github.com/prometheus/common/model/labels.go

@@ -17,8 +17,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"regexp"
-	"sort"
 	"strings"
+	"unicode/utf8"
 )
 
 const (
@@ -87,6 +87,19 @@ var LabelNameRE = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$")
 // therewith.
 type LabelName string
 
+// IsValid is true iff the label name matches the pattern of LabelNameRE.
+func (ln LabelName) IsValid() bool {
+	if len(ln) == 0 {
+		return false
+	}
+	for i, b := range ln {
+		if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) {
+			return false
+		}
+	}
+	return true
+}
+
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
 func (ln *LabelName) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	var s string
@@ -139,6 +152,11 @@ func (l LabelNames) String() string {
 // A LabelValue is an associated value for a LabelName.
 type LabelValue string
 
+// IsValid returns true iff the string is a valid UTF8.
+func (lv LabelValue) IsValid() bool {
+	return utf8.ValidString(string(lv))
+}
+
 // LabelValues is a sortable LabelValue slice. It implements sort.Interface.
 type LabelValues []LabelValue
 
@@ -147,7 +165,7 @@ func (l LabelValues) Len() int {
 }
 
 func (l LabelValues) Less(i, j int) bool {
-	return sort.StringsAreSorted([]string{string(l[i]), string(l[j])})
+	return string(l[i]) < string(l[j])
 }
 
 func (l LabelValues) Swap(i, j int) {