Support for video size to be different from captured picture size.

Adding support to allow video size to be different than the supported
picture sizes. A picture size larger than the demanded video size is
chosen. Captured pictures are then cropped to the size of the desired
video size. Cropping is done from the the center portion of the picture.

Change-Id: I6bcbe16f94b6ecbcf28b7f46826a81b4b6b8cbc3