CameraWrapper: add support for metering mode

Change-Id: Ic192c7fd545759d2d6beb039aba64b60abdb0e21
CameraWrapper: increase size of scene-mode buffer

Change-Id: I6c3564b4c6f246a873900c66bb85a12681ad1f5f
camera: add a workaround for slow camera startup

* On certain devices, the first camera initialisation
  takes long, and fails sometimes.
* Add an app that opens and cloeses the camera on boot,
  so that when the user opens a camera app, it has
  already been initialised and will work.

Signed-off-by: Chirayu Desai <cdesai@cyanogenmod.org>
Change-Id: I0623a0777ad83741c1c36355dffa8adf3a510df3