Arguments were previously "in order" but the keyword arguments are recommended as they are more resilient to msg changes.

This change modifies the behaviour of the driver in case an
unknown packet type is encountered. Previously, the deserialisation
routine would raise an exception, which would cause the driver
to print an error and exit.

In the current implementation the unknown packet type(s) are
stored, their payload ignored, and the driver reports the fact that
unknown type(s) was/were received (with a request to report the
warning, ideally to the package maintainer).

This is not a solution for #16, although that issue prompted this
change.

Updated to catkin.  ur_driver's files were added to nested Python directory for including in other packages.

Added launch directory to bringup package.  Left the old launch files to be backwards compatable for now.  Updated driver with SwRI internal changes.  Changed driver to accept ip address to match ROS-Industrial standard.  IP addresses for industrial robots are typically fixed.  Hostnames are not typically used (this is what the driver expected)