feat(titleService): set pageTitle via state object
  - Removed titleService service, opting for scope variable instead
  - Deleted titleService files and folder
  - Setting 'pageTitle', a AppCtrl scope variable instead, which is bound to the title tag using ng-bind
  - Put the code back into AppCtrl controller, it now makes more sense there since <title> falls under AppCtrl's domain

Closes #55.