Tracker module

Refactored WikiaTracker into an AMD compliant tracker module which is split between two files: tracker.stub.js, which is loaded in the head, and tracker.js which is loaded at the bottom of the page with the rest of the scripts. This makes it possible for us to have the full API available at any point after the head scripts, but with the ability to delay the implementation of tracking functionality and the event tracking calls until DOM ready. Early tracking calls will be spooled and replayed as they always have been.

Along with this work, the WikiaTracker extension has been removed as it is no longer required.

For browser environments, the tracker module will be available as Wikia.Tracker. For CommonJS environments, the tracker will be available as the "wikia.tracker" module.

Thanks to @gabrys for help along the way :)