Improved the dictionary plugin.

- Changed the icon from icon-pause to icon-stop.
- require function can now accept callbacks (for loading SoundManager2).
- Changed from MediaElement.js to SoundManager2.js (better documentation).
- Plays audio files from Macmillan instead of American Heritage (sounds better).
- Added copious amounts of comments.

TODO:

- The audio file expires after some time. If we don't load it by then, we won't be able to play it. Maybe we can put the audio file in a proxy?
Dictionary: The audio file gets preloaded because the link expires very quickly.

- Users who read the definition first might not be able to play the audio file when they're done.
Removed the old spice.js from the dictionary plugin and top_tracks.

- We already have *.handlebars and xspice.js.
Finished Lastfm::TopTracks.

- It uses a helper called "list" to limit the number of items shown.
Merge remote-tracking branch 'origin/spice2' into spice2