Footer is sticky-ified

Here are the code changes to get the footer sticky.  Here's how I did this:

I "inspected element" for the flixter that we have up in heroku and went through the elements that were different and made the HTML match exactly the same.  Then I stole the CSS from the flixter app I had.  Here are the changes that I needed to make.
The `navbar-fixed-top` class changes how the navbar gets placed on the page and makes it so it seems like the navbar doesn't take up space (everything by default is moved ~40 pixels higher).  You could leave this with `navbar-fixed-top` and then also add a margin-top to the `.hero` or just remove the class like I did here.