Venus: proof of concept - SASS concatenation
Oasis: we longer need to support CSS with media set to "print"
WikiaSkin: introduce getStylesWithCombinedSASS method and use it in Venus
WikiaSkin::getStylesWithCombinedSASS - code cleanup
getStylesWithCombinedSASS: update $sassFiles parameter via a reference
Oasis: use getStylesWithCombinedSASS method
WikiaMobile: use Wikia::getStylesWithCombinedSASS and make one instead of four SASS requests
WikiaSkin: create a single AssetsManager instance
WikiaSkin: add a unit test
WikiaSKinTest: make it pass when run in a suite
Remove debug code
Merge pull request #5052 from Wikia/con-1487-support-concatenation-of-sass-files

CON-1487: generic support for concatenation of SASS files