pid: Adding quiet flag to suppress error message

This PR https://github.com/ros-controls/control_toolbox/pull/21 needs to be merged into the ``hydro-devel`` branch in order to allow the change in [gazebo_ros_pkgs](https://github.com/ros-simulation/gazebo_ros_pkgs/commit/4776545954d55749f070eaf95b7d762d5eab0187) to compile. Or perhaps we should not have added that to the hydro-devel branch @jbohren ?

Does this change to PID break abi-compatibility? I know its an optional parameter so in theory no, but this kind of thing perhaps shouldn't be changed in a stable release?

This PR was required for me to build ROS from source.