Revert "Revert "Merge pull request #1896 from Wikia/BAC-709+945""

This reverts commit eb7bf2130244abaa1341e4ffbc17003a83b1459f.
BAC-977 fallback to basic string operations when there is no subdomain sharding for sass files (preview environment)
added comments to clarify getSassFilePath flow
Merge pull request #1937 from Wikia/BAC-977

sasses fallback logic