Fix e-stop bug in joint_trajectory playback

Do not exit example upon finish.
fix subscriber for estop check
fix estop signal listener
fix temporary boolean checks
remove debug comments
pep8 fix
cleanup camera closings
error screen parent assignment could cause infinite recursion in draw
remove leading slash in subscribers and reorder imports
Merge pull request #12 from RethinkRobotics/joint_traj_fix

Joint traj fix