added link from gripper.type_changed to check_calibration
make cuff control example react to new on_type_changed signal
update navigator example for new wheel_moved signal

Now prints the increment as well as the value
moved button signals outside of if statement
added _is_grippable function
fixed pep8 issue
shortened debug statement
Updates per review #22

Pep8 cleanup.
Merge pull request #22 from RethinkRobotics/cuff_calibrate

Cuff calibrate