Tango-happenings

* Django 2.0 & Python 3.x compatible
* Fixed templates for tests
* Fixed URLs not calling views correctly
* Loosened comments dependency
* Removed permalink references

Removed deprecated assignment_tags

* Updated for Django 2.0 compatibility

* Better handling of missing video module

* Improved testing and switched from vobject to python-card-me

* Attempting to import in tags to avoid loading problem.