Upgrade SQLAlchemy to 0.8.0
Include default bg in repo
Search albums & add them as a unit
Add authentication using Persona (BrowserID)

To get the BrowserID JavaScript include not to conflict with the app,
I had to remove JQuery from the Require.js config and load it directly
from HTML.

Currently it behaves like this:

ADMIN_EMAIL set => Must login successfully with that email
ADMIN_EMAIL unset (default) => Anyone with a Persona ID can log in

Static files (/static/*), including hotlinks to music files and cover
art, are currently not access-controlled. This will probably be worth
fixing at some point.
Move ugly button styling out of HTML
Fix verbose option to update command
Sync playlist to LocalStorage
Properly handle no track being active

* If you remove the currently playing song, and it's the last song in
  the playlist, then the playlist seeks to position -1

* Seeking to position -1 sets the "playing song" model's song ID to -1

* When the playing song view sees an ID change to -1, it stops music,
  hides the playback buttons and resets the background image to default

* This commit also fixes buggy behavior when loading an empty playlist
  from LocalStorage