fix (1_7.W001) MIDDLEWARE_CLASSES is not set.
Merge pull request #247 from collinanderson/middleware_classes

fix (1_7.W001) MIDDLEWARE_CLASSES is not set.
Added python 3.4 to tox and fixed Django 1.7 deps.
fix AttributeError: 'TaggableRel' object has no attribute 'to'
fixed field.rel.through AttributeError: 'unicode' object has no attribute '_meta'
makemigrations
Django 1.4 did not support Python 3 yet ;)
Properly serialize through/to in deconstruct.
Fixed test migrations after previous commit.
Fixed dependency to contenttypes.
Test fixes and more 1.7 fixes.
Merge pull request #251 from apollo13/dj1.7

Fixes for #238
Upadted changelog and pushed version numbers.
Merge branch 'develop' of github.com:alex/django-taggit into develop
flake8 fixes
Sort imports

`isort taggit/**.py tests/**.py`
setup.cfg: add flake8 section