* Tidy implementation of validator
* Tests improved and moved to tests/integration (as they call resolve
  internally)

Fixes #614

Distinguish it from the other folders which each define a category of
test.

It didn't exist when I wrote patch_settings but now there's not point
having two versions of the same thing.

Change to products URL was not picked up here.

Also split them into unit and functional tests.

segments.

I added a new validator to oscar.core.validators that validates
absolute and relative URL and checks if the URL already exists. We
use this functionality when creating flatpages in the dashboard to
check if the URL can be used.
The validation includes *two* calls to ExtendedURLValidator to
validate the URL in the first run and then check if it already
exists in the second. This might not be the most efficient way
of handling it. The reason to do it that way is that it reduces
the amount of code that has to be replicated.

This ones won't causes pep8 to complain.

Fixed vanilla import script

* Converted to abstract models
* Added tests for conditions

Wrote a bunch of tests that work around the CatalogueImportException being thrown from the util.py classes
Massive set of changes to the util classes - moved the file checks out to their own class, added a csv reader class, added flush capabilities to flush out the product and stock models before importing, added a mapper to map the csv content against a "model.field" map - this is only very early stages and is currently not finished
Tests for running file checks, but not tests against csv or mapping functionality yet.

This seems to be a simpler and better place for the price calculation at
the moment.  We could introduce a calculator object at some point to
separate the responsibilities.

to the admin and model set-up.