Fix graph command for namespace graphing.

The recent --ungroup option only applies to dependency graphs.
Save As button added along with dummy routine.
Merge pull request #531 from hjoliver/fix-cylc-graph-namespaces

Fix graph command for namespace graphing.
Save function implemented. CLI option removed.
Show/hide cold-start tasks button added.
Merge remote branch 'upstream/master' into cylc-graph-gui-tweaks
Removed old CLI options now present in gui.
Merge pull request #532 from arjclark/cylc-graph-gui-tweaks

Cylc graph gui - enhancements for #514