Update ipython to 6.5.0

Update django-extensions to 2.1.0

Fix example in shipping repository documentation

get_available_shipping_methods must always return an iterable.

Fixes wrong fieldname in StockRecordForm, causing the field to not be removed.

Drop support for category URLs without a primary key.

Fixes wrong fieldname in StockRecord form.

Update uwsgi to 2.0.17.1

Drop backward compatibility for dynamic loading of moved formset classes

Update pymysql to 0.9.2

Update pillow to 5.2.0

Deprecate Range.contains() alias for Range.contains_product()

Update pymysql to 0.9.0

Add compatibility for Django 2.1, and drop support for Python 3.4.

Update django-environ to 0.4.5

Reduce maximum line length in flake8 config to 119 characters.

Drop unidecode and replace with cautious_slugify from Wagtail

Django 2.1 works fine - the only issue was that more passwords
have been added to the CommonPasswordValidator which caused some tests
to fail. I've removed that validator from the test settings.

Remove various deprecated utilities, methods and classes.

See #1674.

Update psycopg2 to 2.7.5

Make license perpetual

Update requests to 2.19.1