automod: rules engine framework (#434)
`automod` is a package to help write moderation automation "rules" to
catch things like spam and flag accounts or content for human review (or
potentially even auto-action).
`hepa` is a simple service which consumes from a BGS firehose and pushes
events through `automod`.
This is an early draft of the rules engine, some notes:
- rules are written in golang here. we might end up using a DSL or
scripting language of some sort eventually
- the framework and some example rules are here in a public repo. we'll
obviously keep some rules and configuration private in the long run
- intention is to use redis for caching and state persistence. will
likely end up with additional datastores