Remove quoting remote ssh commands

Quoting the command argument in ssh is unneccessary.

Old behaviour:

    ssh user@host "/path/to/cylc task started"

New behaviour

    ssh user@host /path/to/cylc task started
Fix gcylc dot view: wasn't plotting non-family tasks in grouped mode.
Merge pull request #361 from hjoliver/fix-gcylc-dot-view-grouping

Fix gcylc dot view: wasn't plotting non-family tasks in grouped mode.
Add group-all/ungroup-all buttons to the graph view tool bar, and ...

... disable grouping to root level, which is essentially useless.
Merge pull request #362 from hjoliver/gcylc-graph-view-grouping-changes

Add group-all/ungroup-all buttons to the graph view tool bar, and ...
Small hot fix: previous change broke right-click menu...

on gcylc dot and text view.
Job submission retries, and new submit-failed state.

Submission failed event hook works too (it didn't before!).
gcylc config and themes changes...

The new submit-failed state required *another* task state color, so:
 1) new default theme with a better separation of colors
 2) backward compatibility: don't abort if a custom theme is loaded
    that does not define the new state color.
Updated cat-log command for new task ID delimiter.
Fix styling of families included in node groups.

Closes #363;
Removed use of non-existent graphviz style 'unfilled'.
Added a comment on visualization with MI.
Added graphviz reference URL to the user guide.
Merge pull request #365 from hjoliver/cat-log-task-id-delimiter

Updated cat-log command for new(-ish) task ID delimiter.
Merge pull request #367 from ScottWales/quotes

Remove quotes from remote ssh command
Removed obsolete task state check functions.
A poll-and-wait option for stop command.

Closes #300.
Consistent help for the suite-state and stop commands.
Allow "inherit=None,parent" to make parent secondary.

Addresses #369
Added some verbose validation output.