Move haproxy httpchk configuration per-listen as zope's webdav returns 401
on (at least) GET / . TCP-level checks are still active, which should be
sufficient.
Also, change zope_family_address_list check to getitem as it's more natural
than concatenating.
Also, stop using apache.zope.backend recipe to add support for per-port
scheme so automatic ERP5Site creation knows which URL is really HTTP.
Also, stop using certificate_authority recipe and call openssl directly
when generating self-signed cert for https/webdavs support.
Also, rework balancer parameters a bit (still undocumented).
Also, make instance-balancer always publish ipv6 value (empty when no ipv6
available), so instance-erp5 always succeeds.