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
Merge branch 'master' of https://git.mozilla.org/b2g/b2g-manifest into default
Bug 891217: add emulator-x86-jb. r=mwu

Change-Id: I8e817250f0c2e307b7a97005b3f451cda193da96
Merge pull request #87 from vicamo/bugzilla/891217/emulator-x86-jb

Bug 891217: add emulator-x86-jb. r=mwu
Merge branch 'master' of https://git.mozilla.org/b2g/b2g-manifest into default