Wikia mobile new ad slots

PLEASE DO NOT MERGE IT YET

I want some eyes on 
ABTesting framework changes

@Wyvek @wladekb - can you have a look ?
@federico-lox @owend @ArturKlajnerok - can you have a look as if this code is sane ? :)

It is rough on edges and I am going to polish it tomorrow - I just want you guys to have a look earlier then later.