Allow for multiple reporting formats

[tarkatronic]

In addition to reporting to Slack channels, it'd be nice to send out summary emails. Maybe we could even report to other systems eventually. Other users of the tool might want to report to Microsoft Teams. Or maybe we could create a reporter that automatically creates JIRA tickets. The possibilities are endless!

The first step will be create a generic Reporter interface, then creating a SlackReporter as a concrete implementation of that interface. From there we can also create an EmailReporter implementation.

[tarkatronic]

I just realized that it would incredibly useful to also have a ConsoleReporter as the default. Grab from GitHub, spit out to the console in a nice pretty format.