added basic user authorization

@RichardBlair 
Updated routing, controllers, and views in adding user authentication to dickbook to match Rails 4.1.1 standards utilizing information from the following resources:

http://railscasts.com/episodes/250-authentication-from-scratch
https://github.com/rails/strong_parameters
and, of course, advice from https://github.com/RichardBlair
My fault again, but this would be simpler if we did:

```
def require_login
  return if logged_in?
  flash[:error] = "You must be logged in to access this section"
  redirect_to root_url #halts the request cycle
end
```