Rotation support

- We only support 0, 90, 180, and 270 degree clockwise rotation

- Some players are known to ignore composition matrix in the MP4 file,
  although this is part of the MP4 file standard.
  Both QT and YT are supporting the rotation

The original patch (65a73f4e) was not merged.
The only change I made is to reuse the same kKeyRotation in MetaData.h;
and thus do not neeed to use kKeyRotationDegree.

Change-Id: Ib328716d4842201c4adf57e4ddfe1f1ac1ae4d8a