Indigo fixes

This pulls all of the recent changes on the hydro branch into the indigo branch, along with the calibration fixes from @kbogert and a few fixes of my own to silence the queue_size warnings that are new in Indigo.

I've tested this on my TB1 enough to verify that the sensors read properly, the robot drives around, and all of the diagnostics are green.

As a follow-up to this, I would like to see a release of the turtlebot_create stack for Indigo, so that Yujin doesn't drop support for it; see https://github.com/turtlebot/turtlebot/issues/170