Emulator now allows fake camera to emulate both, back and front cameras at the same time.
Camera HAL is changed in this CL in order to support this.
Change-Id: I4dcf2d569bb0c6a3800b4a8da5edd4777b5a078a
These two tasks (starting the camera device, and starting working thread that pulls frames
from the started camera device) should be clearly separated, and should not be combined in
one method (as it was with the 'startCapturing' method).
Change-Id: I779bee924d99d9a87257c6b76791545b76795e72