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
When stopping the camera, the working thread should be stopped before sending
"stop" query to the emulator: we don't want "frame" queries to be floating around
while we're in the process of stopping the camera.
Change-Id: I16dc56ca1c2e304a07a074302001d2e27100f2ac
