Crispy-forms-foundation

**Major release to remove deprecated supports**

* Drop Python2 support, minimal Python version support is 3.5;
* Drop support for Django prior to 2.0;
* Drop support for django-crispy-forms prior to 1.8.1;
* Drop support for Foundation 5;
* Ensure support for Django 2.2 and 3.0;
* Ensure support for django-crispy-forms to 1.9.1;
* Removed everything about Foundation 5;

Minor release to add support for Django 2.2

Minor release to fix support for Django 1.11 for ButtonGroup.

This release adds some bugfixes with Abide, new button objects that will replace the old ones a release and Foundation5 support will be removed for the next (non bugfix) release.

Minor release for validating Django 1.11 support

Updated tests structure and documentation to ease development and testing.