Merge pull request #1 from AdamKyle/mark

Learn to Rails, noob.
All but one test are passing.

Currently have one test commented out, thats the admin abillity to select a
role for a user on that users edit page.

Signup now displays appropriate errors.

Login Now displays erros at the top of the page.
Successful Signup goes to Login Path

When you successfully sign up you are taken to the login path.
Extract sign_in controller method, and extracted sessions helpers into StartPoint::ControllerMixins
Remove a semicolon and a dos line ending
Add ApplicationController#authenticate_user! and its specs
Refactor #sign_in method
Begin re-writing users controller specs
Prevent non-admins from deleting users
Add display of errors to edit user form, and fix user role dropdown
Test that admins can update a user role
Fix bug in which a non-admin could update his own role