Switch Nexus 4 to our fork of system/core

Change-Id: Idd04c0fc89a9c3c156821f1f6460415189ca126d
Add helix device support.
There is no necessary to fix the revision of hardware/ril.
Add jb emulator

Change-Id: I34ce0221100e6e6f9c9a8db9600d321f9b078d0f