Cleanup of Video Call pause functionality.

Whether the paused videoState is available is dependent on the carrier's
implementation of the VT spec. The original VT implementation assumed
that this was stored in a system property accessed via InCall; these CLs
move this to a Call/Connection capability which will ultimately support
multisim video capable devices.

- Added new connection/call capabilities.

Bug: 16680364
Bug: 19820114
Change-Id: I3840f92270100811161120dffcfe297bef7c4ea2