Fix/migrate versioning 3.6.8

[Kronos66]

[vuolter]

Hey @Kronos66 I tried this PR and I can actually see the versions dropdown now, but no data are saved in the db table versions when applying changes to the content, so the dropdown remains empty (I see just the entry current).

On a single types (named global in the img below) I got this error, I'm on postgresql:

[Kronos66]

Hey @Kronos66 I tried this PR and I can actually see the versions dropdown now, but no data are saved in the db table versions when applying changes to the content, so the dropdown remains empty (I see just the entry current).

On a single types (named global in the img below) I got this error, I'm on postgresql:

Hi @vuolter, I added support for single types. Could you check this again?

[Christianlance85]

I am getting TypeError: Cannot read property 'listEntityVersions' of undefined when I try to spin it up, but if I remove the first route in the routes.json file, I can spin up my environment, however, it is unable to get the versions of the collection types. Has anyone else gotten this or know how to fix it?

{
      "method": "GET",
      "path": "/explorer/versions/:model/:id",
      "handler": "Versions.listEntityVersions",
      "config": {
        "policies": []
      }
    },

@cyp3rius @Kronos66

[joacimastrom]

What's the status on this @Kronos66 ? I need versioning in an app, if this works it'd be great :)