AlbumInfo: Move to the MPDroid package.

AlbumInfo has no use in JMPDComm, it's redundant of the Album class. It IS
useful as a degraded CoverInfo class.
MPDroid: Code style fixes.
Album: Use a comparator to sort by year.
Album: Improve the SORT_BY_YEAR comparator.

Previously, if a 4 digit year was compared to a 8 digit date, the
comparison would always be less. This helper method will append 0s to the end
of the date if the length of the date is less than 8 and greater than 0. If
the date is greater than 8, the date will be trimmed to 8 digits.
add "go to Album" on songs in search results
add "go to Artist" to menu/songs in AlbumsFragment and SongsFragment