Hipchat adapter + Boltdb store

Hi, we've recently started using Victor to power our company chat bot and I've made a few additions with a few more in the pipeline. Our old bot was node.js but I'm learning go and this is a great excuse. 

Speaking of which, I've only been writing go for about a week. This code works for us but I can't vouch for it's purity or adherence to idiomatic go and I'm happy to make changes as needed.

This pull request includes a chat adapter for [Hipchat](https://github.com/abachman/hipchat-go) and a store adapter for [boltdb](https://github.com/boltdb/bolt).
I'm not sure I understand what `command` is used for here. Could you explain?