Make it more easy to configure Richie redirect on LMS

[igobranco]

Currently, it is required to configure a redirect on the Open edX LMS nginx site configuration.
This module should expose a setting that allows the devops to configure it using a django setting.

It should be a Open edX site configuration or by default an Django setting. Like many other configurations of the Open edx code.

Get inspired by:
RICHIE_ROOT_URL

[igobranco]

We can't do that because when we configure this app like https://github.com/openedx/edx-django-utils/blob/master/edx_django_utils/plugins/README.rst the signals stop working.

Probably would be better to create a new django app eg: richie-openedx-redirect or richie-openedx-login to only install the redirect.

• https://github.com/fccn/richie-openedx-sync/blob/issues/8/redirect/richie_openedx_sync/urls.py
• https://github.com/fccn/richie-openedx-sync/blob/issues/8/redirect/richie_openedx_sync/views.py
• https://github.com/fccn/richie-openedx-sync/blob/issues/8/redirect/richie_openedx_sync/settings.py#L11-L17
• https://github.com/fccn/richie-openedx-sync/blob/issues/8/redirect/richie_openedx_sync/apps.py#L27-L30