Kulungowski robustus

@olegsinyavskiy These changes allow Robustus to use the system ROS installed by the "bstem.ros" package or the compiled ROS and ROS overlay stored on Amazon.  If neither of the preceding are available, then Robustus will build ROS and the ROS overlay and install them in the Robustus cache.  Note that the current version of the ROS overlay stored on Amazon is not compatible with the ROS version installed by the "bstem.ros" package.  Since the size of the ROS component plus ROS overlay has now been reduced to tens of MB, I recommend that B.C. users not install the "bstem.ros" package and instead allow Robustus to use the compiled version on Amazon S3.