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/garyburd/redigo/internal/commandinfo.go

@@ -40,6 +40,15 @@ var commandInfos = map[string]CommandInfo{
 	"MONITOR":    {Set: MonitorState},
 }
 
+func init() {
+	for n, ci := range commandInfos {
+		commandInfos[strings.ToLower(n)] = ci
+	}
+}
+
 func LookupCommandInfo(commandName string) CommandInfo {
+	if ci, ok := commandInfos[commandName]; ok {
+		return ci
+	}
 	return commandInfos[strings.ToUpper(commandName)]
 }