Python 3 and Django 4 compatibility

This is the version compatible with the new stuff.

Remove comparisons to basestring

Some comparisons were done to basestring that's incompatible with PYthon3

Some issues with jQuery

0.3

Conflicts with Django 3.0 admin jQuery impl

Make sure that also the admin widgets are django 3.0 compatible

0.2

Make sure that the admin widget also supports Django 2

First release using tags

0.1

Make compatible with Django >2.1