Per review comments to DM-3690, the configuration should move to YAML with the following goals

• Have a Configuration object that can be tested and passed around
• Redesign the configuration to allow for additional types of message handlers, such as twitter, hipchat/slack, etc.
• Move secret keys entirely into the configuration file
• Provide a configuration template
• Move any sort of hard-coded configuration to the expanded YAML file (e.g., Mandrill templates)