Hubot integration

Here's a branch where I've integrated hubot into the Meteor process.

I've added all the scripts from the `cjb/hubot` repository *except* codex.coffee.  That's what's left to do: port that.  (It would go in `codex-blackboard/server/hubot-scripts/codex.coffee` and would use `Meteor.call` directly instead of going via DDP.)

Fixes: #141