added #track_num and #disc_num
fixed exception caused by m4a files w/o tags
fixed MP3#track_num with v1-only tags
added m4a tests
use the proper logical OR when assigning
spun get_int_pair functionality out to it's own util method
added #user_info
fixed an issue caused when spinning out #get_int_pair
added 8 more attributes

#media, #label, #disc_subtitle, #user_info, #title_sort_order, #artist_sort_order, #album_artist_sort_order, #album_sort_order
preparation for gem publishing
some more cleaning before 0.2.0
Merge branch 'refs/heads/develop'