Hide units that are masked/not-found

Make network links "optional" on update
Add a geard demo

The provided contrib/demo/setup.sh sets up a pre-environment
for the demo, although it needs to be refactored to use all
public images.  Browsing on localhost:14000/scale-1.0/ will
show the state of the loadbalancer.  Also demonstrates mongo
replica sets and OpenShift on top of geard.

Run contrib/demo/demo.sh to run the demo, and
contrib/demo/teardown.sh to delete all running containers at
the end.  Also, will need to clean the /var/lib/docker/vfs/dir
directory to ensure any persisted Mongo data is deleted.
GitHub release script for artifacts