Separate page-actions from #content

Wikipedia admins should be able to style content safely without interfering
with the ui
(see https://en.m.wikipedia.org/w/index.php?title=MediaWiki_talk:Common.css&oldid=559614143)

Introduce MobileTemplateBeta.php to give better separation of our beta and
stable code

Change-Id: I87883d223e4ee99d4d457857a0ccbbeb426f0f42
Merge "Separate page-actions from #content"