[Android]  Add the permission identifies for the APIs of DeviceCapabilities and RawSockets.

  Since the Crosswalk APIs of DeviceCapabilities and RawSockets are supported, need to add
the corresponding permission identifies. This is fix to resolve these issues.

BUG=https://crosswalk-project.org/jira/browse/XWALK-872
Merge pull request #1502 from ShDavidliu/update_permission

[Android]  Add the permission identifies for the APIs of DeviceCapabilit...
[Android] Implement Screen Orientation API through extension (Part 2)

Expose entry points functionality for extension on Android platform, since
screen orientation api is needed to binding to name space "window.screen",
we are using set entry point functionality to implement it like what tizen
is doing.

Add a new construct for XWalkExtension, which won't affect existing extension.