Add verbose option to cpanm builds

Strangely, Device::Serial builds better (at all on rPi) if --verbose is
added to cpanm.  It's actually to have the extra output as well.
Integrate dirtmon; add links to webpage

Track soil moisture and battery voltage from dirtmon sensor and use it
in the determination of whether to run the valves.
Separately, include links to external sources (calendar, cosm,
wunderground) in web page.