Allow first_name, last_name and username params for devise sign_up
Move errors into general errors partial.
Move label styling into layouts stylesheet
Indicate required fields on Post and sign_in forms
Display flash messages in application and admin layouts
Add close to flash messages, adjust padding on flash messages.
Rearrange validation order on User model
Add User factory. Add feature spec for user sign in and sign up.
Adjust flash message close font size