Drag in new songs while listening, drop unwanted songs in trash

*feel free to let this marinate a bit before merging it in, feedback welcome*

### some new additions here, take what you will:
- popup search that allows you to add songs while you're listening,
without interrupting what you're listening to.  [demonstration video here](http://www.youtube.com/embed/v6RFi93SG3Q?vq=hd1080)

- trash can indicator added that responds visually to drag events (highlighting itself as a target), as well as responding functionally to drop events, removing videos that get dropped onto it.

- dev mode:  put '#dev-mode' on the end of your URL, reload the page, and you can develop to your own music without getting interrupted by tubalr autoplaying.

##### recommendation:  peruse graphical changes and adjust styling of elements as you see fit.