HG-156 Add tracking events
HG-156 Fix unit tests
HG-156 Tracking events changes

 * Use tracking function short alias
 * Use default values for all Mercury events
 * Move unit test hack to proper qunit setup function
 * Add “paginate” event
Merge branch master into branch HG-156
HG-156 remove unecessary param from track call
HG-156 change tracking calls to fit new tracking api
HG-156 fix types
HG-156 fix undefined
HG-156 GA _trackEvent argument 3 takes an integer, not string
HG-156 dont need to cast it here
HG-156 add back in isPageView check
HG-156 fix internal tracking and track function
Merge pull request #254 from Wikia/HG-156

HG-156 Add tracking events