SDK / exoplayer

ENCODING_PCM_8BIT support is not required.

AudioTrack.getMinBufferSize does not handle ENCODING_DEFAULT so
switch back to ENCODING_PCM_16BIT.

Issue: #339

The OMX component needs to be configured with a format that has a
MIME type of audio/raw. Remove Ac3PassthroughAudioTrackRenderer,
which is no longer used.

This prevents memory leakage even in the case where the app
is still holding a reference (direct or indirect) to the
Allocator.

Issue: #275

Github issue: #375

This package will house all extractors, which will be unified
to implement a single Extractor interface.

The limit on the ts packet buffer can be reduced during processing
if it's discovered to have padding. Hence we need to reset it back
to the ts packet size before processing each packet.

- Atom related stuff in Mp4Util is moved to Atom.
- Remainder of Mp4Util is renamed to H264Util.

- Keys should not expire during normal playbacks of correctly configured content.
- Attempting to refresh on expiration causes a race condition, that may result
  in either failure or brief re-buffer, for the 30s license test video.
- This change provides deterministic behavior, which is to always fail.