This allows updating code in both places, if necessary. Getting Django
1.5 support would be painful otherwise. This also removes the circular
dependency of django-oscar-testsupport on Oscar.

The requirements were merged. The imports were updated
accordingly. Unused imports in the touched files were removed. No
further changes.

Fixes #376

Also split them into unit and functional tests.

When merging a cookie basket with a user basket, we now set the new line
quantity to the max of that from the two baskets.  This is to prevent
stock rules being violated by merging these baskets.

This allows us to show warning on the basket page when the price has
changed.

Looks up all shipping methods for a basket and picks the first one to
form the estimate.

tests

* Installed the test_extensions app
* Tweaked the basket models and added some basic methods and tests