Added better routing for logging in.

By using guest, intended, and back we can provide a better experience to the users. 

Redirect::guest('login') will store their intended URL in the Session
Redirect::intended('home') will use the stored URL in the Session or the default provided if one does not exist.
Redirect::back() will return the user back the page they were on.

I didn't add back in many places to make sure they get to the correct routes.