Add admin to user table

* Admin is a boolean in the user table
* You can use method admin? to check for admin
* To change the user in rails c, user.update(:admin true)
Admin page

* Created admin controller
* Created admin show page
Create Guest user to allow admin functionality

* Create Guest user
* Add admin? method to Guest user
* Override Monban's current_user in application controller
Merge pull request #3 from elijahkim/admin

Add admin to user table