In a few cases, django.templatefilters.date was used to format a
datetime as string. This filters expects localtime, but was always
passed time in UTC.
Introduced a helper function that should be used instead of the template
filter.

An extension to the offer detail page.  Reminds me how much the
reporting classes need reworking.  Some day soon perhaps...

Using example classes from http://docs.python.org/2/library/csv.html#examples

Fixes #390

The dates should be picked up correctly by Excel now.

on a set of classes.