UC-74 Add error handling on fb user mapping
Also added a helper to use for functionality needed with both fbclient controllers
Merge uconn-1 & refactor usage of fb client model and tracker
Conflict: extensions/wikia/FacebookClient/SpecialFacebookConnectController.class.php
Empty merge
Merge branch 'uconn-1' into uc-74
UC-74 Address CR feeback
CC @garthwebb
Changes to retrieval of fb user id and
Rerouting home if logged in user ends up on special connect page
Merge uconn-1 conflict:
extensions/wikia/FacebookClient/FacebookClient.class.php
Merge uconn-1 again, space fix, conflict:
extensions/wikia/FacebookClient/FacebookClient.class.php
Merge branch 'uconn-1' into uc-74

Conflicts:
	extensions/wikia/FacebookClient/FacebookClient.class.php
Minor change to redirection line
Add mapping related functions to the fb client model
Make use of the fb model methods for mapping users
And clean up the helper
Add facebook session validation
Bunch of followup fixes on fbUserId retrieval
Address feedback from @garthwebb
Merge pull request #5373 from Wikia/uc-74

uc-74 Handle database error + addition of fb client helper