handle file missing in projectgid.rb

a fresh labs instance won't have /etc/ganglia/gmond.conf and thus an error is
printed if the file is missing

/bin/egrep: /etc/ganglia/gmond.conf: No such file or directory
/bin/egrep: /etc/ganglia/gmond.conf: No such file or directory
/bin/egrep: /etc/ganglia/gmond.conf: No such file or directory

Change-Id: Ic91e07eb1e0a887bfb640a035cd7ed140f50eb9d