That roughly speeds up "make sandbox" etc. by a factor of 5-10.

Fixes #655

This allows partners to be identified without using a name that might
change or be translated.

Unfortunately, this involves a few tricky migrations to move data around
in the correct order.

Fixes #434 but reverts work done for #354

This allows a version of the partner to be shown to the customer and
avoids the tight coupling with the wrappers which use the name as a
lookup.

Fixes #354

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

Fixes #390

This involves:
* Better checkout templates
* Updated availability logic for products with no stock
* Updated dashboard templates