It was causing problems with Excel, which didn't recognise it and showed
a strange symbol.  I can't find a compelling reason to keep it, so it
goes.

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.

Replace the import-time nav set-up with a settings-based one.  This is
more flexible ultimately although it doesn't allow extensions to easily
add their node automatically.  However this is probably a good thing
overall as it isn't easy to remove nodes in the previous impl.

Fixes 426

This allows it to be customised via view class subclassing.

Also, made report_form_class and generator_repository views attributes
so they can be more easily overriden.

Fixes #431

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

* Missing template tags
* Incorrect message formatting

Also split them into unit and functional tests.

Features:
* Basic crud
* Stats view

The dates should be picked up correctly by Excel now.

Use the fns in app.dashboard.nav to edit