Better management of pyramid.ini template
In the base image, a template is used to create the pyramid.ini file (https://forge.extranet.logilab.fr/cubicweb/docker-cubicweb/-/blob/branch/default/pyramid.ini.j2). However, some projects started using their own templates (https://forge.extranet.logilab.fr/cubicweb/cubes/fresh/-/blob/branch/default/docker/pyramid.ini.j2 and https://forge.extranet.logilab.fr/logilab/cubes/crm/-/blob/branch/default/docker/pyramid.ini.j2) which do not only seem to be more sophisticated than the base template, but are also the same.
- update the base template
- add template to cube skeletons which includes the base template and says "Add any additional config here when deploying w/ docker"