The path of the python executable used by an instance was parsed from
the shebang of its software release's bin/buildout. But when the path
is too long, the shebang is just /bin/sh and the script starts with
`exec <executable>`.

See merge request !516

Improve hateoas support to show shared instances.

It turns out that ERP5 returns
```
'form_id': {
  'type': 'StringField',
  'key': 'form_id',
  'default': 'InstanceTree_viewAsHateoas',
},
```
for the `form_id` in hateoas, so adapt the proxy to do the same.

Currently hateoas support in proxy only lists non-shared instances,
so this always says that the instances are not shared.

See merge request !511

See merge request nexedi/slapos.core!514

   Set it non-editable

See merge request !513

See merge request !509

   This script isnt used at all

See merge request nexedi/slapos.core!504

   Strict returns directly a single Software Release for a giving url.

   This fast input option aims to allow certain sites, request "related" slaves
   from an Instance Tree.

   The script  InstanceTree_getFastInputDict is used to custom the feature to
   specific software releases, since depends which one is used, and it cannot
   be generalized for now.

See merge request !505

See merge request !506

See merge request !508

See merge request !507

   In this way, the debug becomes easier to be notified.