Possible fix 2.
Compare against os.environ to detect user name override.
Tidy up debug.
Fix splitting bug on '@' in task.py
Merge remote branch 'upstream/master' into fix-ssh-username-bug
Convert gcylc stopped state to str in case it is None.
Merge remote branch 'upstream/master' into fix-ssh-username-bug
Enhanced the broadcast command.

1) Provided an interface to the broadcast expire method.
2) Allowed clearing broadcasts by cycle time or namespace.
3) Rewrote the command help.
Typo corrected in broadcast command help.
Made limitations into features.
Merge remote branch 'upstream/master' into fix-ssh-username-bug
Fix cylc gui log file paths.
Rewrote broadcast command help.
Minor broadcast command help change.
Command help clarification, again.
More broadcast command help tidying.
Remove debug line.
Merge pull request #611 from arjclark/fix-ssh-username-bug

fix for different username on remotes bug
Suite state now documents and validates valid states.
Minor tidying up.