[SysApps][Android] Implement W3C SysApps Contacts API

The implementation is based on 26 August 2013 editor's draft version
http://www.w3.org/2012/sysapps/contacts-manager-api/

Completed features list:
* Save/update individual contact and contacts in batch
* Find/list contacts
* Remove contacts
* Contact change event

Feature: https://crosswalk-project.org/jira/browse/XWALK-49