See https://code.djangoproject.com/ticket/25120

Django 1.9 introduced the AUTH_PASSWORD_VALIDATORS setting which allows for
more flexible password validation. Switch to using that when it is available,
with a fallback to Oscar's previous behaviour in Django 1.8 or when this
setting is empty.

`DEBUG_TOOLBAR_PATCH_SETTINGS` is obsolete in django-debug-toolbar 1.6. We also don't need to specify `DEBUG_TOOLBAR_PANELS` as it is identical to the default.

This fixes a DeprecationWarning

Results in too much clutter in Sentry

This allows the latest.oscarcommerce.com to run with memcache

This sets the Content-Length response header which is required for
CloudFront and possible other cdn's

Since there is no demo or us site anymore we can simplify the structure
somewhat by moving the sandbox one directory up

Example sites now sit in their own folder (sites) for easier
organisation.

This allows members of the public to play around with the dashboard
site.

I'm sick of getting the error emails.

This view has a form that assumes anon checkout is allowed, which it
isn't always.  Treating it as a special case was causing it to be
displayed when it shouldn't.

This makes it much easier to get started when contributing.  The docs
are also updated.

This makes it much easier to get started when contributing.  The docs
are also updated.

This is needed for internal Tangent projects.  The search app in oscar
still needs some work but it works in a very basic fashion at the
moment.

The template for search results still needs attention.

This avoids conflicts with other libraries that use the same trick for
extending templates.

Also added treebeard as a core installed app, as this is needed to get
the templates to be found for the admin.

The session object now has methods for recording that shipping isn't
required for a given order.

Plus created separate update scripts for sandbox and QA builds.