Additional CentOS install tweaks
Additional CentOS install tweaks

Fix a few things in the CentOS installation. Go fully to /var/www, and
use the correct path for geni-portal-install-templates. Remove the
need for a nickname cache now that it's built into the portal.

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