Followup eee88e429e72: method should be named "get_concerned_by"

To allow larger uploads.

We don't need it anymore because bfss has been moved to /etc/cubicweb.d/fresh/bfss

We use bfss to store upload of (mostly) pdf files.
Add a persistent volume claim and mount it in /var/lib/cubicweb/instances/fresh/bfss
To make this work with previous instance we have to rename the instance to "fresh".

In extentities generator, extid is cwuri from database which is a text field.
So in python3 exteid2eid[extid] wasn't matching anything because extid was bytes.
Use text extid instead.

Kubernetes can set a mode using "defaultMode" but cannot mount the file with
other uid than root.
So we have to mount the secret and copy it with good mode and ower in
/etc/cubicweb.d/fresh/cwclientlibrc...

We need to provide a cwclientlibrc file in instance directory

NAMESPACE is intranet, not fresh

We are going to be compatible python 3 only

- update __pkginfo__.py and use cubicweb[pyramid] '>= 3.26.0, < 3.27'
- update README file
- update setup.py to read from README.rst not README

- install from Debian Buster as base image so that we can use Python 3.7
- install current source code for fresh cube
- install additional requirements from docker/requirements.txt

- add docker/entrypoint.sh to define available entrypoints for the instance
- add docker/pyramid.ini.j2 that will be used to create the instance
- add docker/uwsgi.ini that will be used to start the instance
- add .dockerignore file to build a smaller image