Added service to enable and disable tool contact.
Also added service to get robot software version.
This PR requires the changes from PR.
This adds support for tool contact as proposed in #678.
@fmauch the dependency for getting the version is due to test if we expect a "fail" from the client lib or not. An alternative, and maybe better, could be to pass down the robot version from the test launch file so it already knows that version of robots it is testing on. Though it also seems that we only are testing on a UR5e!
I have split this PR in to two seperate PRs. This one now only contains the tool contact functionality. The get version functionality has been moved to PR
This will probably not get merged anymore. This feature exists in the ROS 2 driver, we recommend to switching to that by now.