Pagination with Infinite Scrolling

I have implemented the Pagination Features along with Infinite Scrolling. I also have changed the travis.yml file to enable firefox on travis to run selenium tests.

I have also added the jquery-ui library so that my infinte scrolling library would work but that didn't require any further gems or file downloads since it was bundled with the `jquery-rails` gem.

Also, to use selenium on your machine, be sure to run `selenium install` to install selenium on your machine.