Ronex driver without sudo

To be able to run the RoNeX driver as a normal Linux user (no superuser privileges). We can use the Linux capabilities to allow the involved executable files to get access to the capabilities they need. This gives us increased safety, as we are only granting access to the required privileges. It also can save us some typing.

To run the ethercat driver we need:

sudo setcap cap_sys_nice,cap_ipc_lock,cap_net_raw,cap_net_admin=eip /opt/ros/hydro/lib/pr2_ethercat/pr2_ethercat

To use the nice prefix (used in the launchfile) we need:

sudo setcap cap_sys_nice=eip /usr/bin/nice

Note: Executing the above commands in a terminal window once will set file capabilities until you next update the pr2_ethercat package, after which you will need to set them again.