Bring etcd support for bucket DNS federation

- Supports centralized `config.json`
- Supports centralized `bucket` service records
  for client lookups
- implement a new proxy forwarder

vendor/github.com/ugorji/go/codec/decode_go.go

@@ -0,0 +1,16 @@
+// Copyright (c) 2012-2015 Ugorji Nwoke. All rights reserved.
+// Use of this source code is governed by a MIT license found in the LICENSE file.
+
+// +build go1.5
+
+package codec
+
+import "reflect"
+
+const reflectArrayOfSupported = true
+
+func reflectArrayOf(rvn reflect.Value) (rvn2 reflect.Value) {
+	rvn2 = reflect.New(reflect.ArrayOf(rvn.Len(), intfTyp)).Elem()
+	reflect.Copy(rvn2, rvn)
+	return
+}