Camera: Add a GPS indicator

This will add a GPS indicator to the preview of the photo camera.
The indicator is placed as an overlay at the upper top corner
of the photo camera preview.

It shows one of three icons depending on the GPS state:
    - acquiring fix
    - GPS fix acquired
    - GPS disallowed in system settings

The icon will only be shown in the preview of the photo module,
not in the video or panorama module, and not in the gallery view.

Drawables by blunden.

Change-Id: I0686ef4ee1fe9b34ac9beaaa2bd43555234f4f4d
Camera: Make camera settings transparent

When changing Scene mode or Color effect, it is much more practical to have a transparent menu.
This should avoid the user from closing and opening back the camera settings to check the changes.