/reviewed-on !191

Sometimes, glib is only used as a dependency of pkg-config,
which means it's not used by the instantiated services.

So do not force building Python if slapos.rebootstrap is not used.

The slapos master use different instance-erp5 and instance-balancer than erp5 software release. So I included the monitor changes there as well to fix the issue 

/reviewed-on nexedi/slapos!189

IPYTHONDIR was usable for old versions of ipython, but since project was
renamed to Jupyter the environment variable is JUPYTER_CONFIG_DIR.

Ref:
http://jupyter.readthedocs.io/en/latest/projects/jupyter-directories.html#envvar-JUPYTER_CONFIG_DIR

/reviewed-on nexedi/slapos!188

@luke @Tyagov 

In Jupyter notebooks users could enter the url of their `Base_executeJupyter` function, but [it now gets filled in automatically](https://lab.nexedi.com/nexedi/slapos/blob/2f2a5ad0/software/ipython_notebook/template/ERP5kernel.py.jinja#L10). This makes the `%erp5_url` magic redundant which is why we can remove it. This commit also removes all mentions of `%erp5_url` in the kernel output and `custom.js`.

/reviewed-on nexedi/slapos!185

In the NEO SR, this fixes the permission of the downloaded runTestSuite
template.

Parameters not ready for stabilisation yet

The parameters not ready for stabilisation yet
This reverts commit 1db0265c.

Add functionality to wrapper to ask for an exclusive CPU core.

/reviewed-on nexedi/slapos!184

Helps developing valid software release descriptors.
Allows checking instance parameters and published values against a software
release's schema in addition to validating the schemas themselves against
slapos' schema.json and jsonschema's schemas.

Also, describe a bit more "serialisation" override mechanism: these
properties cannot be made required at schema level, but for any
software-type entry a serialisation must be provided.

it is required for DBD-mysql-4.0.42 with MariaDB 10.1.

This simplistic mail setup does not pass address as command line arguments,
so it is not subject to the vulnerability protected against by this option.

See https://jira.mariadb.org/browse/MDEV-12950 for API changes.

Because this does not seem to be enough:
https://github.com/perl5-dbi/DBD-mysql/pull/133

We should keep using MariaDB 10.1 for ERP5 as long as perl-DBD-mysql
is not fixed properly.