calm now runs on-demand

[Jon Turney <jon dot turney at dronecode dot org dot uk>]

I recently deployed an update to calm which should causes it to run 
on-demand after a maintainer SFTP upload.

Hopefully this reduces the inconvenience of having to wait till the next 
scheduled run, after an upload is made which fails due to some easily 
correctable problem.

calm continues to also run on a schedule at :10 and :40 past the hour, 
so it will still note changes which have been made directly on sourceware.

If you have shell access on sourceware, and make such changes, you can 
force calm to run with '~cygwin-admin/bin/calm scan-(uploads|relarea)'.

Given that, it probably makes sense to consider reducing the frequency 
of scheduled runs.