slapos_metadata_transform_agent: fix data conversion in Stream to Array so json conversion don't fail on special characters

## before

```console
$ slapos service list
List of services:
erp5 /srv/slapgrid/slappart15/srv/project/slapos/software/erp5/software.cfg
slapos-sr-testing /srv/slapgrid/slappart15/srv/project/slapos/software/slapos-sr-testing/software.cfg
slapos-testing /srv/slapgrid/slappart15/srv/project/slapos/software/slapos-testing/software.cfg
hugo /srv/slapgrid/slappart15/srv/project/slapos/software/hugo/software.cfg
metabase /srv/slapgrid/slappart15/srv/project/slapos/software/metabase/software.cfg
dufs /srv/slapgrid/slappart15/srv/project/slapos/software/webdav/software.cfg
```

```console
$ slapos service info slapos-sr-testing
Software Release URL: /srv/slapgrid/slappart15/srv/project/slapos/software/slapos-sr-testing/software.cfg
Instance state: busy
Instance parameters:
{}
Connection parameters:
("<?xml version='1.0' encoding='utf-8'?>\n"
'<instance>\n'
'  <parameter '
'id="environment-script">/srv/slapgrid/slappart15/srv/runner/instance/slappart7/etc/slapos-local-development-environment.sh</parameter>\n'
```

## after

```console
$ slapos service list
{
  "dufs": "/srv/slapgrid/slappart15/srv/project/slapos/software/webdav/software.cfg",
  "erp5": "/srv/slapgrid/slappart15/srv/project/slapos/software/erp5/software.cfg",
  "hugo": "/srv/slapgrid/slappart15/srv/project/slapos/software/hugo/software.cfg",
  "metabase": "/srv/slapgrid/slappart15/srv/project/slapos/software/metabase/software.cfg",
  "slapos-sr-testing": "/srv/slapgrid/slappart15/srv/project/slapos/software/slapos-sr-testing/software.cfg",
  "slapos-testing": "/srv/slapgrid/slappart15/srv/project/slapos/software/slapos-testing/software.cfg"
}
```
```console
$ slapos service info slapos-sr-testing
{
  "software-url": "/srv/slapgrid/slappart15/srv/project/slapos/software/slapos-sr-testing/software.cfg",
  "instance-state": "busy",
  "instance-parameters": {},
  "connection-parameters": {
    "environment-script": "/srv/slapgrid/slappart15/srv/runner/instance/slappart7/etc/slapos-local-development-environment.sh"
  }
}
```


See merge request nexedi/slapos.core!441

because json output is different on python2 and python3 and cli is only
used on python2, we don't test the exact output in python2.

before:

    $ slapos service info slapos-sr-testing
    Software Release URL: /srv/slapgrid/slappart15/srv/project/slapos/software/slapos-sr-testing/software.cfg
    Instance state: busy
    Instance parameters:
    {}
    Connection parameters:
    ("<?xml version='1.0' encoding='utf-8'?>\n"
     '<instance>\n'
     '  <parameter '
     'id="environment-script">/srv/slapgrid/slappart15/srv/runner/instance/slappart7/etc/slapos-local-development-environment.sh</parameter>\n'

after:

    $ slapos service info slapos-sr-testing
    Software Release URL: /srv/slapgrid/slappart15/srv/project/slapos/software/slapos-sr-testing/software.cfg
    Instance state: busy
    Instance parameters:
    {}
    Connection parameters:
    {'environment-script': '/srv/slapgrid/slappart15/srv/runner/instance/slappart7/etc/slapos-local-development-environment.sh'}

This is particularly needed for old OS with python2: very old versions of
pip are trying to install latest version of eggs no matter their python2
compatibility whereas pip 20 is making sure to install only python2
compatible eggs.

See merge request nexedi/slapos.core!433

   Revert inclusion Base_getNodeTitleAndDate and use checked_permission to only get title if the user is allowed to see the document.

   Author is optional so keep empty isn't a problem.

See merge request nexedi/slapos.core!434

Until now, the broadcast address was used for the tun interface instead
of the first address of the range.

See merge request !436

See merge request nexedi/slapos.core!435

  We do want to ignore payments that occur after the at_date.

  We want to know if at a certain date, there still unpayed documents older them that date, if the document is payed after, (and grouped) we unconsider it.

   This was missing to remove since we dropped all mass upgrade code and relies exclusively on Upgrade Decisions.

   Upgrade decisions are also tickets (messages are issued), this makes things consistent with the other tickets (Regularisation Requests and Support Requests)

   This allows administrator see issued messages.

   node_title is another person/organisation title, which was raising if an administrator use himself as sender on the event.

See merge request nexedi/slapos.core!431

If computer partition requested state is `started`, slapos node boot will start
partition services on reboot, event if the node is not able to connect to master or
has no internet.

See merge request nexedi/slapos.core!428

See merge request nexedi/slapos.core!430