added unit test for WallNotificationsController::areNotificationsSuppressedByExtensions()
changed notifications' logic so the bubble doesn't appear when user has no read right
load notifications' assets only when it's a logged-in user and notifications aren't suppressed
changes in unit tests; during that work found some part of code which could have been imporoven
fixed unit test for wall notifications
Merge pull request #1541 from Wikia/DAR-1988

DAR-1988 | Remove notification bubble from WikiaHeader for users without read right