Bug 852583: switch emulator system/core and qemu-kernel to B2G github.

Change-Id: Ibc1989882c27f1fb790474e65ebb7333c93186ec
Merge pull request #66 from vicamo/bugzilla/852583/bluetooth-emulation

Bug 852583: switch emulator system/core and qemu-kernel to B2G github. r=mwu, f=jgriffin