Slack botzo

![tumblr_myoilmi0cz1qd5mq1o1_500](https://cloud.githubusercontent.com/assets/550256/5455639/47989424-850b-11e4-8e2a-ed05ea69b07f.gif)

Makes the Botzo Slack adapter official and phases out HipChat adapter now that we're all slacking.

@articulate/web-ops @plukevdh