Admin roles and layout

Please ignore the former pull request. This one contains everything in that one plus I have promoted your account to admin role. When admins login in, they see an additional "view users" option on the header. On clicking, you can see other users and delete them if you want. Please confirm that "view user" does not appear in normal account my login in with muyiwa@three.com and password muyiwam. 

I couldn't do anything about tests, I still find them confusing. I think you've pretty much done it all, what's left is a well packaged documentation and then pushing to heroku which I'll handle once it's all complete. 
Been up all nite, I had issues with getting the admin header to work, so I may not show up in school today. I'll see if there's any other thing I can add.