Djangomako

- Bump mako from 1.2.0 to 1.2.3

1.3.1-release
- Bump mako from 1.2.0 to 1.2.2

- Dropping support of Django 2 in favor of Django 3.
- Dropping support of python 2 in favor of Python 3 in testing.
- Testing and releasing using Github Actions.
- Dropping CircleCi support.

- Circle 2.0 up and running.
- Upgrade Django to 2.14.
- Add support to python 3
- Fix some function view errors in the demo app.

- Django 2.0 support.
- Ability to define custom template tags.