User registration page is moved to admin.
(non-admin cannot add users.)
Merge branch 'master' into refactor/new-user-to-admin

Conflicts:
	app/controllers/admin/users/registrations_controller.rb
	app/views/admin/application/index.html.erb
	config/routes.rb
Merge pull request #130 from DonutWorks/refactor/new-user-to-admin

User registration page is moved to admin.