Adds support for multi-groups on Motoman Robots

This pull-request adds support for multi-groups on the MOTOMAN ROS package.

This needs the latest version from motoman_driver from @ted-miller

This depends on:
https://github.com/ros-industrial/industrial_core/pull/82

* Succesfully tested on the Motoman SDA10F and on the Motoman SIA10F.
Warn user when default group number is used.