gluster-nagios-monitoring: remove gluster-nagios-monitoring plugin

   removing  gluster-nagios-monitoring ui plugin is as it is
moved to an individual repo at
ssh://gerrit.ovirt.org:29418/gluster-nagios-monitoring.git

Change-Id: I0ba048385f060d9df4a280fce05a77bde322a132
Signed-off-by: Ramesh Nachimuthu <rnachimu@redhat.com>