playbook: no need to remove legacy repositories anymore as it has been a very long time since any machine installed them

Caddy doesn't support the wildcard Virtual Host like Apache so it's not
suitable for standalone deploy.

On newest OS, python2.7 is not installed anymore.

There is not reason to not check endpoint certificate.

Thanks to injecting slapos.networkcache to provided buildout, it will be
possible to use networkcache for fetching the dependencies.

/reviewed-on nexedi/slapos.package!112

/reviewed-on !111

See commit 0421fd9e4dfcedb4754f8df4e51c2656eb78e706 in slapos.git

Since debian/compat is increased to 9, stricter flags are used for compilation.

With default dpkg-buildflags, gettext fails to build as follows:

libcroco/cr-statement.c: In function 'cr_statement_dump_ruleset':
libcroco/cr-statement.c:2610:17: error: format not a string literal and no format arguments [-Werror=format-security]
                 fprintf (a_fp, str);
                 ^

ansible-upload-vm-logs is a Python2 script so we explicitly need requests egg for python2. python-request used to be installed by the deploy script but for Debian 10, the deploy script install python3-requests.

This reverts commit 0acda09c.

I switching to use only one ssh key (luke_chronos_key).

We know that on Debian 9 used version of ansible does not work with success,
so let's make the "when" part depending on the distribution.

/reviewed-on nexedi/slapos.package!108

  Since the upgrade isn't perfectly stable, don't upgrade the package anymore.

/cc @jerome @jm  (You were asking about this)

/reviewed-on nexedi/slapos.package!105

Ces images on été construite pour Teralab.
 La Ubuntu18 a été testée, la debian10 non.
Les fichiers de preseed et les bootcommande font des opérations redondantes.

This reverts commit 0e51aaef.

The latest tag wasn't compiling fine because of erp5-doc still being a
submodule in erp5-vifib branch but not in slapos anymore.