Using wrapped components in a form

I'm trying to wrap a paper component such as paper-autocomplete in my own component and then use it in a form. It works except for setting the form isValid. I tried passing the form to my component, but that throws errors.

This is what I got working:

form:
```
{{#paper-form onSubmit=saveAction as |form|}}
{{user-select ...}}
{{/paper-form}}
```

user-select:
```
{{#paper-autocomplete ...}}
{{paper-autocomplete-highlight ...}}
{{/paper-autocomplete}}
```

This throws errors:

form:
```
{{#paper-form onSubmit=saveAction as |form|}}
{{user-select form=form ...}}
{{/paper-form}}
```

user-select:
```
{{#form.autocomplete ...}}
{{paper-autocomplete-highlight ...}}
{{/form.autocomplete}}
```