installer: fix node quotacheck for non-/ geardata

Bug 1138889 - quota config broken if /var/lib/openshift is a mount point
https://bugzilla.redhat.com/show_bug.cgi?id=1138889

* Fixed faulty sed regex for adding usrquota to /etc/fstab.
* If the mount point had an incorrect selinux label, quotacheck
  could fail due to selinux denials, so run restorecon first.
* Finally, the restorecon of the quota file failed unless the
  mount point is /, so added a / to make it work.