css updated, controller prevents taking a survey twice

I worked on the css with Chris L.  There's a different landing page layout than the standard layout; it has the gorilla background.  Other than that, there were just little tweaks here and there.

I changed some wording.  Also, I added a controller action when a user tried to take a survey.  If they're already taken the survey, it alerts then that they've already taken it and prevents the survey form from loading.