Added Amap(AutoNavi) integration: http://lbs.amap.com (#1164)

* Added support for AMap, aka AutoNavi Map, 高德地图

* Try to include amap error info if failed

* Get correct result from amap response

* Fix result error in amap return

* Refactor codes for AMap handling

* Refactor codes for amap result handling

* Refactor amap handling codes

* Fixed coordinates handling error

* Added tests

* Fixded amap result handling and tests

* Lock webmock on 2.3.2 for ruby 1.9.3 support