Initial dark theme and general theme fixes.

* Hacky workaround for bug #66508
* Got rid of the skins.bluesky.loggedin module (skins/BlueSky/resources/css/loggedin.css) in favor of the new loggedin/loggedout classes for <body>

Change-Id: Ie89a28ed0d5d2e7b0c4b3233b4b5ec14bea33937