Closes #232 - fixing the number of registrations displayed on the admin events page to only show active registrations
Ordering the events on admin/events to sort by starts_at in DESC order
Merge branch 'master' of github.com:andrewhl/AdvancedStudyRoom

* 'master' of github.com:andrewhl/AdvancedStudyRoom:
  allow admins to delete users [closes #224]