Initialize and copy mRotationAngle in VideoFrame

When thumbnails were generated they could be generated at random
angles as the mRotationAngle variable was not initialized to any
value. This variable would have to be explicitly overwritten to not
cause random rotation. Changed the implementation to initialize the
value to 0 (no rotation). mRotationAngle was also missing in the
copy constructor.

Change-Id: I67a5340fdd807c6ab3a3da5eecb09b5b9d5f4666