Add support for audio derivatives

- Add support to transcode audio files to other formats.
  For now only support transcoding to Ogg Vorbis to support
  playback of FLAC, Speex and Opus files in browsers that support Vorbis.
- Support mime-types with codec in player detection (Bug 43249)

Change-Id: I6237b3676d79cadfff8a286f52e3e3289d9c817b
Merge "Add support for audio derivatives"