Drag some Wikipedia domain stuff into the Site class

So it's (mostly) all in one place and changing some code to make it target a LAN wiki is easy.
This means you basically just have to change 5 methods in the Site class to get it to run on your
own wiki. (different API endpoint URL, no HTTPS, no external load.php, change of domain in forLang
and isSupportedSite)

Doesn't touch EventLogging or MobileApp stuff

Relies on I4b54b236

Change-Id: I8ee046f5f5b25b81db4b5b039503e8ec1e11ceb0
Merge "Drag some Wikipedia domain stuff into the Site class"