fixed backward slug data migration, #1689

Fix CSS classes for ProductSelect widgets

Add required fields attributes

Some dashboard.promotions views were missing a fields attribute. For Django 1.8 compatibilty.

ProductSelect widgets in the Dashboard require at least the CSS class `select2`. Django widget tweaks was overriding CSS classes set in the RemoteSelect and MultipleRemoteSelect widgets.

setting date_closed on closing StockAlert, added additional check in …

Fix #1760 -- Update customising oscar docs

Easy: ProductAttributeValue._set_value use six.string_types instead of str.

This should fix #1719.

Fix call to calculate_excl_discount

It was being passed a shipping charge, when it wants a basket.

The impromptu DjangoCon gathering decided it's a good idea.

This is part of addressing #1723. Partner.name is optional. But when we
create a partner through the dashboard, it doesn't make sense to not set
a name. Hence this commit enforces it at the form level.

Closes #1723.

Forbid hyphens in CommunicationEventType code field

Fix validation message in basket

Improve basket validation message

Fixes stockrecord availability validation message in the case when stock is lower than allocation. Previously the message that appeared contained negative numbers. For example: "a maximum of -1 can be bought". Now it will display: "no stock available"

Add migrations required for Django 1.8

When the lowest version of Django we support is 1.8, we can remove these
max_lengths and fall back to the length set in Django (now 254). It's
messy to try and support both Django 1.7 and 1.8 with this change as
'makemigrations' will pick up different things depending on which
version of Django is being used.

Allow the reviews app to be forked with oscar_fork_app

Category model import, minor doc fix.

As the new warning from this PR is acceptable.

The fact that it's embedded in the catalogue app means it needs to be
special-cased.

This commit also adjusts the reviews admin.py to dynamically import
review models - not sure how this wasn't picked up before...

fix for django_oscar issue_#1717