An admin can view applicants/applications

* Modify admin::hall_assignment controller
* Modify admin::halls controller
* Modify routes file
* Admin::applications show
* Admin::applications new
* Users can see notice or alert
* Applicants will see notice for submitted application success
* Applicants will see alert for submitted application failure
* Modify Admin::application show page
* Admin can approve and decline applications
* Modify admin/applications/index to indicate application status
* Modify admin/application controller
* A student can check his/her application status
* Modify admin/application/show
* Modify application index