Merge branch 'release/3.2' into develop

* release/3.2:
  Bump the version to 3.2.
Link to Instakit.

Related: fish2000/instakit#2
Fixed #266 -- Simplified (and renamed) StrategyWrapper.

StrategyWrapper was unnecessarily implemented as a LazyObject
and it triggered a bug in Django (issue 21840).

Changing the lazy object to a function works just as well and
bypasses the bug.
Updated tox.ini to test against Django 1.6.
Merge pull request #268 from bmispelon/tox-conf-update

Updated tox.ini to test against Django 1.6.
Merge pull request #267 from bmispelon/issue-266

Fixed #266 -- Simplified (and renamed) StrategyWrapper.
Added a DeprecationWarning if Async cache file backend is used
Removed unneeded django_rq import
setup.py: added 'async_rq' extra, django-rq dependency

django-rq v0.6.0 is the first version with Python 3 support.
Always call variable "source_file"

This emphasizes that it's a file object and not a PIL image and also connects it
to the earlier example which creates that variable.
Add note about `open()`

Hopefully this prevents people from going through acrobatics to get a File when
they've already got one!
Merge pull request #277 from mkai/_async_deprecation

Added a DeprecationWarning if (old) Async cache file backend is used
Merge pull request #278 from mkai/_rq_async_cleanup

Cleaned up RQ cache file backend code, added async_rq setup extra
Simplified RQ cache file backed by using the job decorator
Merge pull request #279 from mkai/_rq_async_refactor

Simplified RQ cache file backed by using the job decorator
Bump the version to 3.2.1.
Merge branch 'release/3.2.1'

* release/3.2.1:
  Bump the version to 3.2.1.
  Simplified RQ cache file backed by using the job decorator
  Add note about `open()`
  Always call variable "source_file"
  setup.py: added 'async_rq' extra, django-rq dependency
  Removed unneeded django_rq import
  Added a DeprecationWarning if Async cache file backend is used
  Updated tox.ini to test against Django 1.6.
  Fixed #266 -- Simplified (and renamed) StrategyWrapper.
  Link to Instakit.