Adjust setup.py to only depend on Oscar

Django will be installed as one of Oscar's dependencies.
Bring auth fixture in line with Oscar's
Add support for a local settings file

I want to use real postgres rather than spatialite for development and
so I need a way of overriding the default DATABASES setting.
Tidy dashboard templates

* Better breadcrumbs
* Use reverse_lazy in views
Remove field.html partial

Think we can use Oscar's instead.
Tidy store list view

* Add column headings
* Make name a link to public page

Fixes #34
Add breadcrumbs to public-facing pages