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/helper_unsafe.go

@@ -0,0 +1,49 @@
+// +build unsafe
+
+// 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.
+
+package codec
+
+import (
+	"unsafe"
+)
+
+// This file has unsafe variants of some helper methods.
+
+type unsafeString struct {
+	Data uintptr
+	Len  int
+}
+
+type unsafeSlice struct {
+	Data uintptr
+	Len  int
+	Cap  int
+}
+
+// stringView returns a view of the []byte as a string.
+// In unsafe mode, it doesn't incur allocation and copying caused by conversion.
+// In regular safe mode, it is an allocation and copy.
+func stringView(v []byte) string {
+	if len(v) == 0 {
+		return ""
+	}
+
+	bx := (*unsafeSlice)(unsafe.Pointer(&v))
+	sx := unsafeString{bx.Data, bx.Len}
+	return *(*string)(unsafe.Pointer(&sx))
+}
+
+// bytesView returns a view of the string as a []byte.
+// In unsafe mode, it doesn't incur allocation and copying caused by conversion.
+// In regular safe mode, it is an allocation and copy.
+func bytesView(v string) []byte {
+	if len(v) == 0 {
+		return zeroByteSlice
+	}
+
+	sx := (*unsafeString)(unsafe.Pointer(&v))
+	bx := unsafeSlice{sx.Data, sx.Len, sx.Len}
+	return *(*[]byte)(unsafe.Pointer(&bx))
+}