Fix no youtube video results bug
Change youtube script to use robot.http
Store timeout ID so we can clear in shutdown

Fixes #523
Don't load roles.coffee if using auth.coffee

This will not load roles.coffee if HUBOT_AUTH_ADMIN is set, this assumes you are
using auth.coffee if it is set.

Fixes #518
Simplify version parsing
Remove tweet.coffee from hubot-scripts.json

Requires users to add the ntwitter to package.json which is a hurdle to simply deploying to heroku.

Fixes #527