Adding Django 1.10 support

[moacirmoda]

All tests are passing!
It needs to be addapted to older versions.

[coveralls]

Changes Unknown when pulling 58fb5ad on moacirmoda:master into ** on st4lk:master**.

[coveralls]

Changes Unknown when pulling 58fb5ad on moacirmoda:master into ** on st4lk:master**.

[st4lk]

Hi Moacir,
thanks for PR!

I see that only Django 1.8 tests are passing. But Django 1.9 have following error:

InvalidTemplateLibrary: Invalid template library specified.
ImportError raised when trying to load 'crispy_forms.templatetags.crispy_forms_field':
cannot import name memoize

I think we can drop support for Django 1.7.
But we need to add support for Django 1.10 (add tests for this version).

[moacirmoda]

Hello... i think that if we update django-crispy in 1.9 the build can work.