Bugid 95356 - Oasis Tracking

Adding additional tracking to the Oasis skin:
https://wikia.fogbugz.com/default.asp?95356

This branch also contains some cleanup to WikiaTracker. The old methods "track", "_track" and "trackClick" have been removed and two new methods have been introduced: track and buildTrackingFunction.

The purpose of track and buildTrackingFunction is to consolidate trackEvent wrappers to one location and provide an easy way for modules/plugins to implement tracking methods with default parameters. A quick look through our codebase shows that this functionality has been [duplicated](https://github.com/Wikia/app/blob/dev/extensions/wikia/WikiaBar/js/WikiaBar.js#L384) in [many](https://github.com/Wikia/app/blob/dev/extensions/wikia/WikiaPhotoGallery/js/WikiaPhotoGallery.slider.mosaic.js#L13) [different](https://github.com/Wikia/app/blob/dev/extensions/wikia/WikiaHubs/js/WikiaHubs.js#L35) [places](https://github.com/Wikia/app/blob/dev/extensions/wikia/SpecialContact2/SpecialContact.js#L40). Instead, it can be implemented [like so](https://github.com/Wikia/app/pull/363/files#L9L50).