We also try to switch the tests to use python -m unittest as a way of
invoking tests, instead of the deprecated python setup.py test

Adds the newly added to nexedi's repositories rubygemsrecipe (https://lab.nexedi.com/nexedi/rubygemsrecipe) to the list of tested eggs.

/reviewed-on nexedi/slapos!693

and make sure we really use the develop version, by clearing version pin
that might be for another version.

Also clean up comments in version section.

This will be needed for standalone tests.

slapos.core test suite needs `sensors` command in $PATH
nexedi/slapos.core@7467ef4c (comment 71574)

/reviewed-on nexedi/slapos!479

Those values are free to be used by tests in order to obtain working
IPv4 and IPv6 addresses.

/reviewed-on nexedi/slapos!470

Some tests need to play with IPv6, and it would be better, if they would use
IPv6 on which the test system has control.

/reviewed-on nexedi/slapos!467

/reviewed-on nexedi/slapos!450

Instead of letting `python setup.py test` install the depencies, use
buildout way of installing the eggs.

This software use `interpreter` recipe of `zc.recipe.egg` to install a
python with all eggs pre-installed. This is a way to get all the
dependencies at install time instead of getting them at run time from
pypi when running `python setup.py test`.
`erp5.util.testsuite` has been extended to support a parameter to
specify which python interpreter to use.

One issue is that this way of installing eggs by buildout cause chicken
and egg problem: cloning repository containing `slapos.recipe.cmmi`
needs git, and to compiling git needs `slapos.recipe.cmmi`.
The consequence of this is that re-running software will install too
many parts again.
One solution for this would be to clone `slapos.recipe.cmmi` with a
`git` command provided by testnode or system package.
Another solution would be to not install `slapos.recipe.cmmi` develop
egg, simply install the egg from it's current pypi version while
installing the software (running tests will be from the git checkout
anyway).
For now this is open issue.

Another point of attention is that `python setup.py test` install the
requirements listed in `test_requires`, but `zc.recipe.egg` does not
provide a way of installing these. Some of our packages have `[test]`
entrypoints, in this case, the software installs the test entrypoints.
For others, we install the eggs.

Other improvements:
 * use a simple `slapos.recipe:wrapper` instead of `slapos.cookbook:egg_test`
 * fix the typo in repository name erp5-util-repository ->
   erp5.util-repository ( this mean we will have to fix the test suites in
   nexedi ERP5 )
 * document "what is this software" and a scenario of how this software
   can be used to develop slapos eggs.
 * switch to buildout-hash.cfg for easier template hash management.

This is a follow-up of commit 5c980caf,
now that the new code of the 'wrapper' recipe is used (1.0.58 released).

  CFFI is added on this directory, and it is required to bootstrap slapos.toolbox.

  slapos.package is not an egg anymore, it's implementation was replaced by
    the usage of ansible with playbooks.

Fix usage of _ that was depreprated on the recipe, with the upgrade it it got broken.

This is a workarround to circunvent setuptools/distutils conflicts when run python setup.py test for the first time.

It allows to develop and test the egg inside of the slapos instance.

Add back egg_test recipe

It currently tests slapos.core, slapos.recipe.build, slapos.recipe.template.