Ensure correct polkit config written for RHEL6

Ensure the correct polkit config is written for RHEL6, or nova-cpu
will fail to start with libvirt permission errors

Change-Id: I871ef4e03157883db15be41222b7338765fbb843
diff --git a/lib/nova b/lib/nova
index f28094e..3a59681 100644
--- a/lib/nova
+++ b/lib/nova
@@ -297,7 +297,7 @@
 
 
         if is_fedora || is_suse; then
-            if is_fedora && [[ "$os_RELEASE" -le "17" ]]; then
+            if is_fedora && [[  $DISTRO =~ (rhel6) || "$os_RELEASE" -le "17" ]]; then
                 sudo bash -c 'cat <<EOF >/etc/polkit-1/localauthority/50-local.d/50-libvirt-remote-access.pkla
 [libvirt Management Access]
 Identity=unix-group:libvirtd