(feat) Scraper to pull the top 1000 github users

Gets data for the leaderboard(s) from the top 1000 users returned from a search to GitHub (above a certain number of repos and followers, to cut down the search; sorted by followers).

Scrapes data from the users' profile pages, e.g. :
{
    "full_name": "Tom Preston-Werner",
    "username": "mojombo",
    "location": "San Francisco",
    "join_date": "Oct 19, 2007",
    "popular_repos_stars": 7398,
    "primary_language": "Ruby",
    "contributions": 63,
    "followers": "17k"
  }

The handler for the stats .json is not yet set up. scraper.js is intended to run perhaps nightly via a cron job.

Also adds comments in various places.

To do:
- Most popular repos
- Some esoteric languages are probably underrepresented in the stats, need to fix this.
- Find a way around the search API limits?