[openni_wrapper] Using right environment to launch cameras on different machines.

This assumes that everyone followed the install instructions and installed everything to `/opt/strands/strands_catkin_ws`
After this has been merged you can run the chest camera on a different pc with something like:
```
ROSLAUNCH_SSH_UNKNOWN=1 ROS_MASTER_URI=http://linda:11311 roslaunch openni_wrapper main.launch machine:=left-cortex user:=strands camera:=chest_xtion
```
Replacing the linda specific master uri and machine name.