Update msg.sends to use robot.name instead of hardcoded hubot
Replace username/password auth with token auth.

This let's us use request_id in places, so when you look at PagerDuty,
it reports which user ack/resolved, instead of the logged in user.

As part of this, needed to rename HUBOT_PAGERDUTY_APIKEY to
HUBOT_PAGERDUTY_SERVICE_API_KEY.