Refactor CSS / UX PR

Refactoring the CSS on the site by removing the Foundation gem and replacing it with regular CSS and JS files from the Foundation framework. This allows for easier editing and debugging. With the PR, I hope to address the various CSS bugs listed in #20 such as cross-browser issues and broken mobile views. I also hope to implement a cleaner admin page in preparation for the admin page overhaul and some UX improvements. I'll request a review and merge once I've finished everything.