Introduce an service to tell apache to reload its config.
This uses `hash-files` feature of slapos.cookbook:wrapper to get this
process restarted everytime something change in apache configuration
files.
This service wait forever to prevent reloading apache everytime slapos
node instance is running but only when something actually changed.

balancer instanciation is supposed to fail when zope partitions are not
instanciated yet - add a comment in the failing lines to explain that
it's expected.

`enable_authentication` parameter of `backend-list`
was not documented.

This reverts commit f5e9c89a95a04333db5fbe8fdc5d33e92852205d.

This reverts commit b535d46e6f6e06bf8416585cece958284c8eb228.

This reverts commit ca91499e382eef779b94a6150ca47c54244fd86d.

https://bugs.launchpad.net/zope2/+bug/699865

firefox > 52 is needed to allow ignoring ssl certificates errors with
geckodriver

We don't want runUnitTest is to listen on 127.0.0.1, as it is not
allowed for SlapOS instances. Another reason for the change is because
we are using userhosts, name resolution of localhost was done on DNS
server and not all DNS server resolves localhost.

Because zelenium tests needs to access this zserver over a secure
origin, add an https proxy in the balancer for tests.

Document the existing behavior that setting mariadb.test-database-amount
to 0 disable the creation of testrunner, now that it also controls the
generation of one balancer entry.

stack/slapos.cfg: Add slapos.extension.shared. This extension creates .shared file in software directory as a mark of software that was built with shared feature.

This usage of textwrap.dedent *sometimes* does not work and sometimes
create files with indentation, so we don't have "#!/bin/sh" as first
line but "    #!/bin/sh"

Use a "safer" version that should work in all cases.

perl path does not need extra /bin

See nexedi/jio@4b8bddba

Rework perl installation to install each package in a separate directory.

Each package install a `perl` interpreter for each package, which is implemented a shell wrapper setting `$PERL5LIB` with the path of this package and its dependencies.

To install a perl package, use `perl-CPAN-package` macro, like in this example for a fictional `XXX::YYY` package:

```
[perl-XXX-YYY]
<= perl-CPAN-package
module = XXX/XXX-YYY
version = 1.2.3
md5sum = ab68b329da9893e34099c7d8ad5cb9c940cd123
```

This will download package from https://www.cpan.org/modules/by-module/XXX/XXX-YYY-1.2.3.tar.gz and install using the usual `perl Makefile.PL && make && make install` sequence.

To install package with dependencies, use the `inc=` argument, like in this example for  another fictional package `XXX::ZZZ` package that would depend on `XXX::YYY` and `XXX::ABC` :

```
[perl-XXX-ZZZ]
<= perl-CPAN-package
module = XXX/XXX-ZZZ
version = 1.2.3
md5sum = 401b30e3b8b5d629635a5c613cdb7919

inc = ${perl-XXX-YYY:site_perl}:${perl-XXX-ABC:site_perl}
```

The full list of options is described in the [macro](https://lab.nexedi.com/nexedi/slapos/blob/a5bec95c/component/perl/buildout.cfg#L31-65).


That macro creates an interpreter for each package, but sometimes we need to create an interpreter with multiple packages. The `perl-wrapper` macro is available for this. It also accepts a `inc=` argument in the same format. Because this wrapper is implemented using `-I` argument, it is also suitable for scrips running in perl [taint mode](https://perldoc.perl.org/perlsec.html#Taint-mode-and-%40INC), like the w3-validator we are using.

All perl components and perl usages have been updated to this new infrastructure.

Some (apparently) unmaintained components were using an obsolete `slapos.recipe.build:cpan` recipe. They were used only in mioga2 from unstable, so I moved them inline in mioga2 software.

/reviewed-on nexedi/slapos!341

( mostly because old version is no longer on CPAN )

( mostly because old version is no longer on CPAN )

We stop using slapos.recipe.build:cpan , but these unstable components are
not ready and not being actively maintained, so move them inline in
mioga software, which was the only user of these components.

When the work on this is resumed, we should switch to perl-CPAN-package
here as well.

Generate a wrapper with all dependencies available

${perl:location} is now a perl without any package, components using
perl with one specific package must switch to using the perl with the
dependent CPAN packages installed.

Installing everything in site_perl is not the "buildout way" and is
incompatible with the upcoming shared slapos.recipe.cmmi

  This version contains optimisation for restore (and a bit for backup), specially in case of large sets of unmodified files.

this parameter is used for external service like saucelab to access test url

Drop support for Go 1.8; Add support for Go 1.10 and make it the
default.

It comes a bit late because previously we were hitting
https://golang.org/issues/24285, and so have beeing waiting for
nexedi/slapos.core!42 to be
deployed there on slapos nodes everywhere.

As of 9 Aug 2018 it seems that deployment has been completed.

/reviewed-by @alain.takoudjou, @rafael.
/reviewed-on nexedi/slapos!372