Docs: Minor tweaks to getting started guide

A few little bits caught my eye. Moved the django-compressor tip nearer
to the section about INSTALLED_APPS.
Docs: Recipe for getting Solr up and running with Oscar

I struggled, so I thought I'd document it.
Allow unassigning categories from products

This has been impossible so far. It is easily achieved by setting
can_delete=True on the formset.

I spent some time trying to get the nice solution working, which would
be that assigning an empty category means deleting that ProductCategory
instance. But I haven't found a good solution that avoids problems like
in #1267. I have since come to the conclusion that enabling can_delete
is the right thing to do. One can then explicitly hide the checkbox,
but set the correct hidden field in Javascript on the client side if
an empty value is assigned.

The fields section has been moved from the factory declaration to the
ProductForm Meta class to allow for easier customisation.

Fixes #1289
Correct Sphinx syntax in shipping docs

Underscore does not seem to have meaning in Sphinx, was rendered as-is.
Abstract base classes for shipping models

This is a common and useful Oscar pattern, and there's no reason to not
use it for the shipping app.

They are not imported anywhere in Oscar and just provided for
convenience, so no imports had to be altered.
Tests and fix for BrowsableProductManager

The changes in 10bfa701 renamed get_query_set to get_queryset, which is
a change that only happened with Django 1.6.

A simple alias fixes the issue. Also added some tests for the manager.

Fixes #1294
Drop legacy ShippingMethod name

Changing a unofficially deprecated model name is clearer than having
three places to get at the same model.

The name 'AbstractBase' is consistent both with our naming of other
abstract models, and lots of apps having a Base class.
Merge pull request #1296 from tangentlabs/fix/abstractshippingmodels

Abstract base classes for shipping models
Add release notes for abstract shipping classes

Those are the release notes for the changes in #1296

Intentionally did not link the new document from the index because 0.7
isn't released yet.
Make demo site in Travis

This ensures that we catch errors in the build process of the demo site,
and led to me spotting #1294.

I must've accidentally committed my demo database settings; switched to
a more generic defaults in demo/settings.py. Also added ATOMIC_REQUESTS
as that is recommended by Oscar.

django-extensions' reset_db fails with PostGIS without a template
database, hence it is skipped on Travis.
https://github.com/django-extensions/django-extensions/issues/489
Drop Python 2.6 support

We need to bump the version of django-dynamic-fixture to get the test
suite to run under Python 3. They've dropped Python 2.6 support in the
same release.
Upgrade sorl-thumbnail & django-dynamic-fixture for Python 3 support

sorl-thumbnail unreleased version trips when THUMBNAIL_DEBUG isn't set.
I've submitted a pull request to fix it.
Minor test suite fixes for Python 3 compatibility

TestCase.assertEquals (note the s at the end) has been deprecated.
The only failing tests remaining are CSV related, which is not
surprising.
Add Python 3.4 to list of supported Python versions

Tests currently don't pass, but I'm hopeful they will in time for the
release of 0.8.
Fix a few lint errors
Fix Sphinx warning from PhonenumberDescriptor docstring
Stop performing a full re-index immediately after restarting Tomcat

I've started seeing "Connection refused" errors which I can't recreate.
It is possibly as Tomcat isn't ready for the re-index when the script
requests it. The Oscar cronjob will trigger a re-index when it gets to
it.
Remove useless entropy-increasing calls of django.conf.urls.patterns

The function essentially does two things:
1. it applies a prefix - the first argument - to the given urls. In no
   instance a prefix was given
2. it calls url() for simple tuple or list elements in the given iterable.
   Cases where such a tuple or list was passed to patterns have been
   replaced by direct calls to url()

2 allowed for both calls to url() and simple tuples to be listed in
get_urls() and similar places. This allowed for unnecessary variation.
Always calling url() makes the url lists look less noisy and more uniform,
allowing the reader to focus on the actual differences of the urls instead
of superfluities.

django.conf.urls.patterns will also undergo deprecation starting from
Django 1.8. This commit anticipates that change.

https://docs.djangoproject.com/en/dev/releases/1.8/#django-conf-urls-patterns
Merge pull request #1300 from machtfit/cleanup-urls

Remove useless entropy-increasing calls of django.conf.urls.patterns
Added missing part of license for third party code