Major re-factoring

The big idea of this pull request is to move away from the extension sandbox and into the Songza space via web accessible resources.

Key bindings are done by directly calling player instance methods.
Buy button is rewritten to use the iTunes lib access the "View in iTunes" functionality.

This preliminary rewrite does not yet offer query caching, search refinement if prior search has failed, and button disabling if no amount of search refinement returns results, all of which are upcoming.