Add support for displaying album art images in both library browser and queue using Universal Image Loader for Android library

I figured out how to do pull requests. Here are the list of changes I made:
- Add (fairly cheesy) music notes image to be used when album art is missing (you may want to change this)
- Update manifest and add application class to initialise image loader library
- Create new library row layout to be used for headers (no art image) and modify existing layouts for both expandable and non-expandable rows to include album art
- Add method to Song class to return URI for album art
- Update Queue adapter to use a view holder to recycle views for better performance. Add image loader calls.
- Add image loader to Media adapter to be used for both album and song media