Allow to Add CPU or RAM in hotplug mode, without need of restart qemu process

Remove old and non used debian images, use debian9 image by default now

@alain.takoudjou , @rafael  this fixes broken webrunner tests.

Passing one: https://nexedi.erp5.net/test_result_module/20180126-5FF058E7/2

/reviewed-on nexedi/slapos!277

@Nicolas , @rafael , @klaus  please review.

/reviewed-on nexedi/slapos!276

@rafael , @Nicolas , @klaus  please review. It's followup of !272 

/reviewed-on nexedi/slapos!275

 zc.buildout version up to 2.5.2+slapos012
 slapos.recipe.template version up to 4.3
 slapos.core version up to 1.4.4

My mistake from 1b540151 (golang: Infrastructure to build Go workspaces / projects)

/reviewed-by TrustMe

If we don't specify MaxRequestWorkers, it seems like Apache 2.4
errors with:
AH03490: scoreboard is full, not at MaxRequestWorkers. Increase
ServerLimit.
Maybe because MaxRequestWorkers then defaults to a too high value
compared to ServerLimit and ThreadsPerChild.

/reviewed-on nexedi/slapos!263

This is useful to being able to peek for low level site result details.

getWorkingSet() is slow and it is not always needed. So, it is better not to call it in __init__.

Revert "slapos/recipe/librecipe/generic.py: GenericBaseRecipe's _ws is a lazy attribute now."

This reverts commit 281d3774.

getWorkingSet() is slow and it is not always needed. So, it is better not to call it in __init__.

When git repositories are in detached head, `git symbolic-ref` cannot be used.

In this case, `gowork-snapshot` outputs `fatal: ref origin is not a symbolic ref` and create a buildout profile with empty revisions.

After these changes, we try to get from a remote named origin in this case. If this did not work, we output the problematic repository.

I added some minor "cleanups" at the same time.

/reviewed-on nexedi/slapos!268
/reviewed-by kirr

because other variables are vertically aligned

When git repository is in detached head, there's no symbolic-ref, so we
cannot anything better that assuming there's a remote named "origin"

This reverts commit 6cb00ff0,
because of a regression in InnoDB (https://jira.mariadb.org/browse/MDEV-14614).
Several functional tests started to fail with 10.2.12.

As currently it fallbacks to system's gettext

While testing this merge request : nexedi/erp5!243

The following test was failing for me : https://nexedi.erp5.net/test_result_module/20180107-664D9A6/13

Since numpy is not added as a dependecy for h5py. the testnode didn't upgraded numpy while upgrading h5py. 
Adding numpy as a dependency should fix it

/reviewed-on nexedi/slapos!267

Fixes all cloudooo being given the same port, because of jinja2 variable
scoping.
Also, move to buildout.hash.cfg for md5sum maintenance ease.

Also update README accordingly.
Its becasue now erp5-site is being created automatically using software-type
default and there is no create-erp5-site software-type anymore.

In the particular case of PATH, '' is the same as '.',
which is a bad idea from a security point of view.

instance-erp5.cfg.in:
  quoted values should not be part of the configuration parameters
    https://lab.nexedi.com/nexedi/slapos.toolbox/blob/beb86eab2dee7178aa6e4795da0f56bb6cacaea1/slapos/apachedex.py#L62
  modify default apachedex parameters
    --erp5-base +erp5 .*/VirtualHostRoot/erp5(/|\?|$)
    --base +other /
instance-balancer.cfg.in:
  option `--configuration` should be used instead of `--config`
    https://lab.nexedi.com/nexedi/slapos.toolbox/blob/beb86eab2dee7178aa6e4795da0f56bb6cacaea1/slapos/apachedex.py#L76

instance-mariadb.cfg.in:
  rename slowquerydex folder to slowquery_digest
mysql-querydigest.sh.in:
  exit 1 on error
  add date to the output file name of pt-query-digest to fit promise behavior
    https://lab.nexedi.com/nexedi/slapos.toolbox/blob/beb86eab2dee7178aa6e4795da0f56bb6cacaea1/slapos/promise/check_slow_queries_digest_result/__init__.py#L29
  review sh arguments handling
  end message: "ok" -> "Report generated successfully." or ..."failed with code $?"

https://cgit.freedesktop.org/fontconfig/commit/?id=1ab5258f7c2abfafcd63a760ca08bf93591912da

fontconfig > 2.12.1 now requires gperf.

This reverts commit 38123b86.

fontconfig was not building any more on many machines (most testnode machines). Revert
until investigation is done.