Removed information about releases < 1.7.
Merge pull request #1973 from haikoschol/master

Removed information about releases < 1.7.
Fixed #21445 -- Clean up misuse of null in quickElement.

Thanks to trac user parsch for the report.
Fixed #21012 -- New API to access cache backends.

Thanks Curtis Malony and Florian Apolloner.

Squashed commit of the following:

commit 3380495e93f5e81b80a251b03ddb0a80b17685f5
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date:   Sat Nov 23 14:18:07 2013 +0100

    Looked up the template_fragments cache at runtime.

commit 905a74f52b24a198f802520ff06290a94dedc687
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date:   Sat Nov 23 14:19:48 2013 +0100

    Removed all uses of create_cache.

    Refactored the cache tests significantly.

    Made it safe to override the CACHES setting.

commit 35e289fe9285feffed3c60657af9279a6a2cfccc
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date:   Sat Nov 23 12:23:57 2013 +0100

    Removed create_cache function.

commit 8e274f747a1f1c0c0e6c37873e29067f7fa022e8
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date:   Sat Nov 23 12:04:52 2013 +0100

    Updated docs to describe a simplified cache backend API.

commit ee7eb0f73e6d4699edcf5d357dce715224525cf6
Author: Curtis Maloney <curtis@tinbrain.net>
Date:   Sat Oct 19 09:49:24 2013 +1100

    Fixed #21012 -- Thread-local caches, like databases.
Fixed #21488 -- Multiple locales treatment in i18n commands.

Removed multiple locales separated by commas variation (that wasn't
working as documented) in favor of simply allowing use of the
``--locale``/``-l`` options more than once for ``makemessages`` and
``compilemessages``.

Thanks Romain Beylerian for the report and Claude, Simon for their help.

8750296918072c97a51f6809d19828ce3f1b8d40 from stable/1.6.x.
Allowed running the test suite without memcached (!)
Simplified iteration in HTTP response objects.

Fixed #20187 -- Allowed repeated iteration of HttpResponse.

All this became possible when support for old-style streaming responses was
finally removed.
Fixes #21412 -- Better error message for messages.add_message

Problem were users calling messages.debug/info/* with a wrong argument
and getting the error "You cannot add messages without installing
MessageMiddleware"

Thanks to trac-user merb for the report.
A handful of flake8 fixes
Fixed #21200 -- Consistantly raise errors across all cache backends.

Thanks to tchaumeny for the patch.
Fixed #21486 -- Prevented settings config in signal connection

This was particularly problematic in the chain get_wsgi_application
-> db.connections import -> signal connection -> settings configuration.
Thanks Jon Dufresne for the report.
Follow up to e112654fc81ddb3fbffbb8382b004d69367a85fe

Actually comitted the code now :þ
Don't fail if cPickle doesn't exist.

Today is not my day :(
Fixed test breakage under python 3 introduced by a480f8320a5b36501bfd0e8cd70b8dc04adf2d08.
Add missing commas in Prefetch docs
Merge pull request #1980 from krallin/patch-1

Add missing commas in Prefetch docs
Removed confusing comment from the docs.

The settings reference documentation doesn't seem the right place to
invite users to write their own database backends.

Also the actual wording makes the task sound trivial, which is hardly
the case; writing a custom database backend is a very difficult task.