Remove traces of StrAndUnicode

This shift brings us closer to a Python3-first code base.
Bump version to 0.7.3
Merge branch 'master' of git://github.com/machalekj/django-datatable-view into feature/genericipaddressfield
Add external dictionary of model field classes

This should allow external customization of how field classes are
treated, particularly for external field from third-party apps, and
fields that we need to dynamically detect, such as the overlooked
``GenericIPAddressField``.

This closes #53 and address #49, although in the latter case, we may
still eventually want a way to register a field type “category” into
the dictionary with a set of trailing ORM query bits that can be
applied to support unknown extensions to the query language.
Merge branch 'feature/genericipaddressfield'
Bump release to 0.8.0
Add explicit skip of Manager values

This addresses #57, where Django 1.7 has allowed ManyToManyManager to
become callable, but requires a ``manager`` keyword argument.  This
opens a can of worms we don’t really care about, so we now skip a value
if it is a Manager that got past the callable() check.
integrate generic field types patch
remove unnecessary double counting queryset with blank search field