W3C Telephony API implementation.

Implements the latest W3C Telephony API specification found at http://telephony.sysapps.org/
Requires the oFono telephony middleware and the BlueZ Bluetooth middleware for working with paired phones.

BUG=XWALK-1419
CreateConferenceCall

Create sounds heavy and like something with multiple steps... why not just StartConferenceCall ? or Initiate... but that sounds a bit heavy as well