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 html, css, 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
HTTParty and Canvas_lti_controller changes are included to show how a Canvas API call can be made to return JSON

LeaderboardController.js is mostly commented out because it is not sprint specific
https://jira.ets.berkeley.edu/jira/browse/CYB-41
@NolanChan , it's pretty typical to put deployment-specific configurations (notably URLs, security tokens, etc.) in a YAML file. CalCentral picks up configurations from an outside-the-source-code YML  file whose name is based on the RAILS_ENV (e.g., "development.local.yml"). The config ends up in a global named "Settings". E.g.:

https://github.com/ets-berkeley-edu/calcentral/blob/master/app/models/cal_link/proxy.rb
or, using signet/oauth_2/client : 
https://github.com/ets-berkeley-edu/calcentral/blob/master/app/models/canvas/proxy.rb

Since Data Cultures is using Rails 4 from the start, you might have different configuration technology options than CalCentral had. But it would be good for you & @coyote to figure out a project configuration approach very early on -- hard to get far without DB passwords, etc.