Add client caching for GitHub requests (#129)
GitHub responses are now cached and requests are made conditionally when possible. This reduces the request load Bulldozer places on GitHub and avoids hitting rate limits. Cached requests are always re-validated with GitHub to avoid working with stale data. The maximum size of the cache is also configurable by administrators.
Add support for Github Checks (#110)
Bulldozer now correctly considers checks created with the GitHub Checks API when considering pull requests for merging. This change requires accepting new permissions to lookup check status and listen to check_run events.