active admin integration for super admin

Active admin integrated for managing user.

Major change is removed old gem used in rails 3 (<b>protected_attributes</b>) and using rails 4 default one. Reason for that is active admin for rails 4 won't work unless. Because of this change implemented <b>strong parameters</b> in all controller.

Note : 
  bundle install
  rake db:migrate
  rails s

To access admin page goto <b>base_url/admin</b>
default admin credentials are
<b>
admin@example.com
password
</b>