Update the prep script.
Update the prep script.

Change the install dir to /usr/share/geni-ch. Upate gcf installation
to gcf-1.6.1.

charliemeyer/geni-portal,tcmitchell/geni-portal,charliemeyer/geni-portal,charliemeyer/geni-portal,charliemeyer/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal,charliemeyer/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal