[Meta] Firefox for Android

[NikkelM]

In a first step, general support for Android should be added, but optimally, the mobile YouTube page should also be supported. This has a different layout, and perhaps events, so the DOM handler must be updated accordingly

[NikkelM]

http://m.youtube.com/?persist_app=1&app=m to force mobile page (persistent), and http://www.youtube.com/?persist_app=1&app=desktop to go back to desktop