Fix various colorization issues in Monobook

This commit addresses several color problems in the Forum and WikiaStyleGuide extensions caused by pulling colors set in the Theme Designer for the Oasis skin.
Fix out-of-place black background
Additional colorization fixes (VOLDEV-36)
Merge branch 'dev' into VOLDEV-36

Conflicts:
	extensions/wikia/Forum/css/RelatedForumDiscussion.scss
enforced VOLDEV-36 changes
VOLDEV-36: Separate Monobook styling
VOLDEV-36: include mixins
Merge branch 'dev' into VOLDEV-36

Conflicts:
	extensions/wikia/Wall/WallHistoryController.class.php
Add newlines
Merge pull request #2792 from WikiaVolDev/VOLDEV-36

VOLDEV-36: Recent changes filter and Forum quotes use incorrect style from Theme Designer in Monobook