Because slapos.core hardcodes a "supervisord.socket", this file happens to be deleted and cause bugs

Revert "resilient: new paramater to define the time to sleep before running the backup in the cron job."

This reverts commit 30d1a937.

It includes more debugging lines, not deploying a slapproxy (no need anymore thanks
the free-port selection recipe), and not delegating some work to a cron job.

In gunicorn v19.6 and v19.5, a bug was introduced which deletes socket when nginx worker exits.
In our case, it crashes the slaprunner and prevents it from restarting by slapos.
Let's stick to v19.4.5 until this issue is closed : https://github.com/benoitc/gunicorn/issues/1298

Default is a random value between 0 and 6 hours. KVM and Slaprunner test instances set it at 0.

  Version up only goes to buildout2 case, buildout 1 series keep the same.

For sftp to work we need to define sftp "subsystem" on server side in
sshd speak. Sftp support in turn allows for sshfs to work.

NOTE

	Subsystem sftp internal-sftp

won't work because we are doing games with ForceCommand and reexecution
of "$SSH_ORIGINAL_COMMAND" (see previous patch for details).

2a733418 (slaprunner: replaces dropbear by openssh) switched slaprunner
sshd from dropbear to openssh (thanks for it once again) and used
ForceCommand to imitate login shell to be partitions `${bash:location}/bin/bash -l`.

For case when original ssh command is explicitly provided
("$SSH_ORIGINAL_COMMAND" is not empty) the code there tries to just
execute what was provided by caller.

However the reexecution is not completely correct as for cases when
origin command contains some quoting, 1 level of quotes is removed.

The case when I hit this in practice is git access to repositories over
ssh. When git wants to e.g. clone a repository it runs `git-upload-pack
quoted-path-to-repo.git` and fails this way:

```
$ GIT_TRACE=1 git clone ssh://host1/~/B.git
19:28:23.558858 git.c:350               trace: built-in: git 'clone' 'ssh://host1/~/B.git'
Cloning into 'B'...
19:28:23.572994 run-command.c:336       trace: run_command: 'ssh' 'host1' 'git-upload-pack '\''~/B.git'\'''
fatal: ''~/B.git'' does not appear to be a git repository
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
```

Quoting SSH_ORIGINAL_COMMAND and evaluating it completely via eval fixes this.

/cc @Nicolas, @alain.takoudjou

Slapos.toolbox has a new dependency to pycurl, which fails to compile if libcurl cannot be found. This commit adds the component/pycurl dependency to most of the Software Releases which have a dependency to slapos.toolbox.

I tried to do it globally, so I couldn't check the compilation of all the modified SRs. Is it a way to test that all SRs still compiled ?

Also, did I forget some important SR ?

@rafael @alain.takoudjou @kazuhiko @jm 

/reviewed-on nexedi/slapos!97

Openssh (sshd) doesn't want to start with keys generated by dropbear

slaprunner: updates export script to make sure that etc directory exists in backup before copying into it

When it is restored on importer instance, it erases its RSA key... Which makes the sshd service to crash

slaprunner: uses sshkeys_authority recipe to manage openssh keys, otherwise they may change at any slapos run

This makes easier the development of the webrunner, as it can be deployed within a webrunner

Changes include:
  * new parameter "no-ipv4-frontend" to prevent the request of an ipv4 frontend. The webrunner cannot provide one, so let's get rid of failing promises.
  * new paramaters to define the ports of the ssh servers (for runner-importer and runner-exporter). Then no colliding when servers run on the same IP.

Revert "slaprunner: fix resiliency test, add development-mode (bool) parameter for easy build webrunner in webrunner"

This reverts commit 59966611.

slaprunner: fix resiliency test, add development-mode (bool) parameter for easy build webrunner in webrunner