fetch data from a list of repos, and store that on s3

* [x] load list of watched repos from config
* [x] fetch basic info about those repos
* [x] update list of forks
* [x] update list of pull requests (both open and closed)
* [x] update list of issues (both open and closed)
* [x] store in .json file posted to data.codeforamerica.org s3 bucket