Add new phone type DO NOT MERGE

This CL adds a new phone type: PHONE_TYPE_THIRD_PARTY. If a 3rd party
app implements android.intent.action.THIRD_PARTY_CALL_SERVICE then
this phone can connect to it and have it implement all the
functionality.

This should be useful for VOIP apps that need to use the native call
UI.

With this patch things like the call log, mute, speaker phone work.
Things that aren't implemented yet are:
  - hold and conferencing
  - DTMF
  - post dial

I'm currently testing this by patching PhoneFactory and creating an
instance of ThirdPartyPhone as the default phone. I'll send out a
CL later to dynamically choose the phone based on available services.

Change-Id: I40f53da12d4b1ebdb88b7a8b0969789be8fd4b7c