Django-instant

Add support for Darwin in the installer by tboulogne

Minor fixes and updates in doc

Maintenance release: fixes for Django 2:

- Add cors headers
- Fix `is_authenticated()`
- Fix default handlers path

+ a new frontend is available

Feature release: the handlers for declared channels can now be located either in the project templates dirs or in the apps templates dirs. Thanks to tboulogne for the help

Maintenance release:

- Update urlresolver path for Django 2.0: thanks to tboulogne for the PR
- Add tests
- Linting

Maintenance release: an important refactoring has been done to prepare the arrival of the database channels in version 0.7

Fix the `get_channels` templatetag that broke the frontend with the new declarative channels initialization