Bundle our custom ExoPlayer components into aar instead of directly
depending on the project. This just makes things far better regarding
ease of use and reproducible builds.
Expose a custom MediaButtonReceiver that handles the media button
intent. This is not because I wanted to implement this. Some apps
like gadgetbridge just blindly query ACTION_MEDIA_BUTTON instead of
relying on the more modern MediaController API, which I expected
most apps would use instead.
Resolves#62.
Use a custom ExoPlayer fork with the FLAC extension enabled. This
greatly improves the listening experience, as it enables metadata
support on OGG files and FLAC files to be played below API 27.
