Gutterball hibernate

This branch removes mongodb from gutterball and instead uses hibernate. Liquibase support has been added to create the DB schema.

Reviewers:  Please take your time with this review. We need to make sure that the model is solid. Keep an eye out for any bits of data that we may want to store but has been left out. I've tried to verify along the way, but feedback was limited.

So we're storing entire events, but not really using that data, it's just for futureproofing?