Update Last.fm icon in preferences
Add NSDate+TimeAgo to podfile
Add Last.fm popover that shows 10 most recent tracks
Append Last.fm icon instead of replacing other links
Add ability to love/unlove song from Last.fm popover
Add preference for showing the Last.fm button
Add preference to automatically love/unlove a track on Last.fm based on thumbs up rating (fixes #83)
Update Last.fm API keys
Fix timestamp alignment in Last.fm popover