Building on the work of @ArtS

This check now happens in the product itself to avoid the extra SQL
queries involved.

A liberal application of `select_related` and `prefetch_related` is a
useful thing.

Installation issues with virtual-node and virtual-less

Alter how absolute discounts are applied

After ``oscar.catalogue`` from ``ui.js`` in
768311780b its init statement was
not removed causing the JS to fail.

This change applies the discount to all matching lines in the benefit
range, weighting the discount by the line prices.  The old way was to
iterate over each line and try and apply all the discount.

This new way means that applying an absolute benefit consumes more
products from the basket than the old way, which may possibly have some
confusing side-effects.

This change avoids an issue where customers can get a free product if
they return most of the ordered products apart from the one that was
discounted to zero.

You only want to compile Less files if you are developing the CSS of
Oscar.  Most people don't do this and so we default to serving
compressed CSS without Less compilation.  This also means that
the many contributors don't need to bother installing node.js and lessc,
which makes the installation process much simpler.

This change also re-introduces the `USE_LESS` setting which controls
whether Less files are used or not.

They are only really required if you are developing Oscar's CSS files -
they are not a real dependency of Oscar.

Not quite sure how it regressed in the catalogue app.  Git blame does
not help sadly.

From #591

From #591

Add language switcher to main navigation

Use dropdown in the top nav.  This still needs some FED attention as it
doesn't render quite right atm.

* Use en-gb as default
* Correct order of middleware

Conflicts:
	oscar/templates/oscar/dashboard/orders/order_detail.html

* Add defaults
* Put source name as a normal column

Mark-up was wonky.

Installing the requirements.txt after running 'setup.py develop' can
cause problems as it doesn't respect the version ranges from setup.py.
This was picked up by Hudson which was installing Django==1.5 when
upgrading django-nose.

This is addresses by:

* Adding Django to requirements.txt
* Running 'setup.py develop' AFTER installing requirements.txt

Improve many translated strings across Polish language file

Conflicts:
	oscar/locale/pl/LC_MESSAGES/django.po

Conflicts:
	oscar/apps/catalogue/abstract_models.py

It seems to belong conceptually there, rather than on the ProductReview
model.

Plus some light tidying of the views module

Bring names inline with normal django conventions.

* Extract out the review snippet into its own partial.
* Bring the review detail inline with the review list template.

Had fallen out of sync with the core product URLs as it still used a
hyphen instead of an underscore.

Some commenting and indenting added.

Haystack's SearchView isn't based on django CBV and uses 'page' instead
of 'page_obj' in context. Simple fix was to duplicate pagination.html
and use that version for the search view.

/howto/index.rst was pointing at the wrong file. Renamed the file to
maintain naming consistency.

Yet another project is hard to maintain, and it's mainly used for
internal use. Removing it reduces the number of options of how to get a
Oscar project running, hence making it easier.

Allows for easier overriding when changing what gets displayed.

It conflicts with the nose restriction required to get the spec plugin
working.

Resolve pickle error for ProductAttributesContainer

The merged branch had a migration with number 0017 which clashed with an
existing one.  This commit renames the migration so it is applied
correctly in order and picks up the changes from the preceding
migrations.

Fix #581