Run ERP5 tests under [usershosts](https://lab.nexedi.com/nexedi/userhosts) wrapper with the same host mapping as zope instances.

This will allow to simplify configuration of services such as memcached and also be a more realistic environment.

This revealed problems with userhosts, at least on Debian 9,  that have been fixed in nexedi/userhosts!2 , so at the same time we update userhosts to get these fixes.

/reviewed-on nexedi/slapos!303

To get fixes from nexedi/userhosts!2

The main reason is to fix inkscape segfaults that break ERP5's svg to
image conversion.

We are supposed to have valid certificates and if really needed,
slapos.recipe.build:gitclone can ignore it.

reviewed on nexedi/slapos!300

thx @jerome

Depending on host python version the string "Build successful" renders
differently, so do not be too smart for it and simplify it.

In all examples of custom.js the Jupyter variable is capitalized, but
here it was not. Because of unknown reason, without Jupyter upgrade,
it stopped to working. Switching from "jupyter" to "Jupyter" fixes the
problem.

So that we can use name aliases such as `erp5-memcached-volatile` during
tests.

A quick slapos profile for Grafana, InfluxDB and Telegraf.

/reviewed-on nexedi/slapos!286

This change unexpectedly break tests which uses supervisord running supervisord. @gabriel is confirming.



/reviewed-on nexedi/slapos!299

In order to track issues with software deployed in VM, provide more
introspective information about the VM itself.

This is needed for example for wendelin.core arrays + connections
See slapos.core@b5a1e352

/reviewed-on !297

- overwrite slapos.cookbook:request.serialised with slapos.cookbook:request
- corresponfing md5sum updated

/reviewed-on !298

/reviewed-on nexedi/slapos!291

configure: WARNING: unrecognized options: --with-wepb

It is not needed to follow KVM development blindly and be hit by
bugs during the development.

If provided, shows instance name value in the title, so it is easier to track
and relate shellinabox with a webrunner.

/reviewed-on nexedi/slapos!295

@kazuhiko @arnau This reverts commit bf7c13c6.

/reviewed-on nexedi/slapos!296