This is required starting erp5.utils 0.4.51

Also add a missing md5sum for instance.cfg.in

/reviewed-on nexedi/slapos!362

Fixes:

 * skip tests for parts which won't be fixed
 * fix assertion for master partition
 * fix typos
 * parameterize headers depending on frontend type

This reverts commit 8e24f3ab.

QUIC has issues with client certificate authentication, detected by chance.

  As this is used by the tests.

  As this is used by the tests.

If the version is unpinned, the buildout will fail. It is currently mandatory to
  keep all the eggs pinned.

  Any development environment can se allow-picked-version to true if they were tryting to check
  upgrades of some eggs.

This were already discussed and agreeded and the test already passed:

[20180611-4AD45F1D](https://nexedijs.erp5.net/#/test_result_module/20180611-4AD45F1D)

/cc @jerome @jm 

/reviewed-on !363

Enables QUIC protocol https://github.com/mholt/caddy/wiki/QUIC

/reviewed-on nexedi/slapos!360

Follow changes in erp5.util that will allow for stable test lines.

reviewed on nexedi/slapos!310

  The development speed of cloudooo is quite stable, so there are
  no reason to preserver the cloudooo unpinned.

/reviewed-on nexedi/slapos!361

 * improve links
 * add gathered information about upstream for some items
 * fix formatting

/reviewed-on !358

It is application/json no text/json.

Cf nexedi/slapos!358 (comment 63538)

Desipte of original analysis the middleware plugin is not needed, as Caddy's
http.rewrite + http.proxy is powerful enough to set headers depending on the
header regular expression.

This will ease further development

In those places caddy_custom_https (and it's backward compatbility companion
apache_custom_https) was not checked, thus making it impossible to just use
https customisation, without http one.

caddy_custom_http and caddy_custom_https are implemented and exposed
instead of apache_custom_http and apache_custom_https, but with backward
compatbility for the latter form from apache-frontend.

In TODO mark missing usage of custom http found during work on this commit.