Android: fix two race conditions in the media player.

start() could be called before the media player was marked as prepared.
When changing media, setMediaPath() could be called before the media
player was reset.

Task-number: QTBUG-34558
Change-Id: I886fd5f5008f76dcbc88c57d7b16a439b394d4a7
Reviewed-by: Christian Stromme <christian.stromme@digia.com>
Android: use correct format when capturing a picture to a buffer.

Don't decode the JPEG data to raw RGB using QImage. QCameraImageCapture
reports anyway that JPEG is the only supported buffer format.

Change-Id: Ib17760e4361b004775c002b686ef7529b3768aab
Reviewed-by: Christian Stromme <christian.stromme@digia.com>