Allows ACLs/settings in model config

/to @bajtos @ritch 

The PR allows acls and other setting properties to be specified in model-config.json.
In fact, I had the code to group the model settings into a `settings` or `options` but thought it needs to be consistent with the model definitions.

I'm happy to add `options` back. One idea is to allow `static` properties to be described in LDL. The settings model can then be used for model configuration prompts. For example,

```json
{
  "name": "User"
  "properties": {
    ... instance properties go here
  },
  "staticProperties": {
    "ttl": {
      "type": "number",
      "default": 3600
    },
    "emailVerificationRequired": {
      "type": "boolean",
      "default": false
    }
  }
} 
```