Remove ephelper and other endpoints code.

appengine/ephelper/epfrontend/json.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package epfrontend
-
-import (
-        "encoding/json"
-)
-
-type jsonRWRawMessage struct {
-        v   interface{}
-        raw []byte
-}
-
-var _ interface {
-        json.Marshaler
-        json.Unmarshaler
-} = (*jsonRWRawMessage)(nil)
-
-func (m *jsonRWRawMessage) MarshalJSON() ([]byte, error) {
-        if m.raw != nil {
-                return m.raw, nil
-        }
-        return json.Marshal(m.v)
-}
-
-func (m *jsonRWRawMessage) UnmarshalJSON(data []byte) error {
-        m.raw = data
-        return nil
-}