fix not all model properties getting rendered

- root problem is that the datatype select component
would fail if the data type is not a string
- the user had some properties defined as arrays:
eg: type: ["number"],
- added logic to try/catch the value setting and reset to
string if it errors out.
- also added updated properties iteration to update model
to make sure model properties get updated explicitly during
model save
Could you please extract the code building a property to a new helper `given.propertyInstance()` helper?

```js
var propConfig = given.propertyInstance({ modelId: created.id, type: ['number'] });
```

Since the helper can be invoked multiple times, the property name should be unique - use the same mechanism as in `given.modelInstance`.