Add run.sh script for running with cron

Includes setting up virtualenv, environment, logging etc.
Finish writing tests & fix bug

Update the sample data so it's a bit more interesting in the period
we're looking at.

Fix the max precipitation which was incorrectly getting the minimum!
If min/max precipitation are the same, just show 1

ie instead of `0.4-0.4mm` show `0.4mm`
Only attempt SMS if recipient list is non-empty
Tweak to output format, show zero as 0

ie show 0-0.5 rather than 0.0-0.5