Graphite-beacon

- Upgrade tornado and drop Python 2.6 support (144)
- Improvement: Fail-fast with better error messages on fatal errors (e.g no config file)
- Bug fix: Add default backwards-compatible config.json for Docker (134)
- Bug fix: Include pyyaml by default and use YAML config loader for `.yaml` files (143)
- Bug fix: Ensure `time_window` is honored when `until` is non-zero. Previously, the value
of `until` would reduce that of `time_window`. (147)

- Improvement: use `validate_cert` for URL alerts (111)
- Improvement: better incident key and `client_url` for pagerduty handler (109)
- Improvement/bug fixes: enable persistence for the telegram handler and various bug fixes (130)

- Bug fix: don't crash due to lack of SIGHUP on Windows (94)
- Bug fix: access dict correctly in hipchat handler (96)
- Improvement: Allow slack notifications to users (100)

- Added 'minimum' and 'maximum' methods
- Allow alerts to be defined in multiple config files

- Fix issue 46;
- Support `until` option for Graphite queries;
- Customize alert behaviour with no data;
- Enhance expressions (support AND/OR);
- Added VictorOps handler;
- Better Slack notifications;
- Added `public_graphite_url` option;

- Support YAML in config files.
You should have install `yaml` and use `<filename>.yml` as config files.