This way we don't need to vendor python-redis (so we don't need to
update it for python3 support).

This also change the options in a backward incompatible way:
 - options are now kebab case ( server_bin -> server-bin )
 - a new cli-bin option holding the full path to redis-cli command
 is required to enable promise

Prevent unexpected instance deletion.

32fbf0d4 (recipe/postgres: support non standard port, 2021-11-12)
broke support for empty port, it was generating config file with
`port = ` , which is an invalid config file syntax for postgresql.

even though the recipe has a required option for port, it was not used
and server was always listening on default (5432) port

slapos.cookbook recipe tests sometimes manipulate buildout eggs working set,
which will install packages from pypi. makeRecipe utilty function was
guessing buildout egg folders by parsing builout.cfg, but since a33844a2
(slapos-testing, slapos-sr-testing: Don't duplicate instance.cfg prologue
that is already provided by stack/nxdtest/instance.cfg, 2021-03-22),
these are defined in an extended profile, so this stopped working.

Instead of this fragile pattern, make the test software release pass the eggs
directories with an explicit environment variable.

use six for python3 compatibility

So that the test fail if they are missing.

See !739

If for example the ip changed, this recipe needs to re-generate
configuration files.

unlike what I assumed, env argument of ConfigParser.get does not work as
dict.get, it has priority.

This broke the case of SLAPOS-EGG-TEST

Rewrite this using ConfigParser.has_option

Now that we also run slapos.cookbook tests from SLAPOS-SR-TEST we cannot
simply examine buildout.cfg, because unlike SLAPOS-EGG-TEST this
repository is now checked out in parts of the software folder, not the
instance folder.
So that trick of looking up the egg directories in buildout does not
work, because this is a software buildout.cfg ... instead, we assume
that the standard eggs and develop-eggs directories are used.

Use json.dumps/.loads to generate promise plugin code. This is safe as it will correctly escape sring and prevent code injection from untrustable parameters.

Add 'import' parameter to simplify parameters used to generate the script instead of passing full import code. When import parameter is set, promise will be loaded from that import path and parameter `content` is ignored.

/reviewed-on !515

/reviewed-on !480

Using
https://python-jsonschema.readthedocs.io/en/latest/validate/#versioned-validators
instead of a local copy of json schema

It is combination of requestoptional and serialised.

In order to avoid needless inheritance create JSONCodec and use it, also
with renaming Serialised to RequestJSONEncoded.

Also provide a test asserting that important log is seen in case if no expected
return is set.

Add testfixtures module to catch logging.

To be compatible with buildout (and not only `slapos.recipe.template:jinja2`)

See [#20180416-1138FFA](https://nexedi.erp5.net/bug_module/20180416-1138FFA/)

---

Running this buildout:

```
[buildout]
parts=x

[userinfo]
recipe = slapos.cookbook:userinfo

[x]
recipe = plone.recipe.command
command = echo "Hello user id ${userinfo:pw-uid}"
```


In a slapos patched buildout it outputs: `"Hello user id !py!991"` (which means it's not usable for references directly in other buildout parts)

In a "non patched" buildout fail with error:

```
While:
  Installing.
  Getting section x.
  Initializing section x.
  Getting option x:command.
  Getting section userinfo.
  Initializing section userinfo.

An internal error occurred due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 2127, in main
    getattr(buildout, command)(args)
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 681, in install
    [self[part]['recipe'] for part in install_parts]
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1278, in __getitem__
    options._initialize()
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1376, in _initialize
    self._dosub(k, v)
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1431, in _dosub
    v = '$$'.join([self._sub(s, seen) for s in v.split('$$')])
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1495, in _sub
    v = self.buildout[section].get(option, None, seen)
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1278, in __getitem__
    options._initialize()
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1386, in _initialize
    self.initialize()
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1395, in initialize
    self.recipe = recipe_class(buildout, name, self)
  File "/tmp/x/eggs/slapos.cookbook-1.0.62-py2.7.egg/slapos/recipe/userinfo.py", line 13, in __init__
    options['pw-uid'] = pinfo.pw_uid
  File "/tmp/x/env/lib/python2.7/site-packages/zc/buildout/buildout.py", line 1520, in __setitem__
    raise TypeError('Option values must be strings', value)
TypeError: ('Option values must be strings', 991)
```

/cc @Nicolas @alain.takoudjou  @vpelletier 

/reviewed-on !321

This function factorize the code to instanciate a recipe in a fake
buildout.
The new feature is that if running in a buildout directory, the recipe
will reuse the eggs from this buildout instead of trying to install eggs
again.

thx @jerome

inotifyx does not support Python 3.

Test will fail if /tmp/instance_test_resourcefile already exists