Added queue_size parameters to prevent ROS Indigo warning

Fix for https://github.com/RethinkRobotics/baxter_examples/issues/32. See discussion at #38.

This PR merges all of @davetcoleman's changes into development rather than master. I also changed the queue_size of the joint_command publisher to be 1. This ensures the only joint command messages that are ever used are the most recent.