Added Monitor to WaterModel.

Monitor has been integrated with Xia's SendEmail project.
Monitor will execute if WaterTap is automatically shutdown due to lack
of Water. Email will be sent to an address.

Still missing: Choice of Email address. At this moment it will send from
my Gmail to my private Email. 

Statistics:
Added a statistics class to WaterModel.
This class will insert a statistics reading into statisticsDB at every
reading. 

StatisticsDB scripts have been uploaded to Dropbox.