CYB-41 Mock Data is fetched and shown on the Leaderboard

Added AngularJS leaderboard controller and factory, as well as integrated @ericayin 's front-end leaderboard and javascript code.
Leaderboard Factory fetches data from a url and displays on front-end
Also included some small style issues not covered in https://github.com/ets-berkeley-edu/datacultures/pull/3

https://jira.ets.berkeley.edu/jira/browse/CYB-41