[Runtime] Add Widget Access Request Policy (WARP) parsing handler for
WGT package.

Add a WARP handler into the WGT package parser. The WARP spec reference
link is: http://www.w3.org/TR/widgets-access
Merge pull request #1704 from takethathe/warp_handler

[Runtime] Add Widget Access Request Policy (WARP) parsing handler for WGT package.