* Refactoring, namespaces, cleanup

This is the first patch in a series to refactor Zero Mobile extension.
* All classes moved to inclueds/ dir
* All classes moved to \Extensions\ZeroRatedMobileAccess namespace
* Removed unused ZeroRatedMobileTemplate
* ZeroRatedMobileAccess.body.php spltted up into two php files:
   class ExtZeroRatedMobileAccess => PageRenderingHooks.php
   class ZeroRatedMobileAccess => ZeroSpecialPage.php

Change-Id: Ic043db9d54cc39b975bcd9caaf08cb218ee5acec