Provide option to render autocomplete results in html input fields

AutoCompleteSelect fields should be able to render the selected result in the input field rather than the deck below the input.

Specifically, given the example lookup field defined by:
```python
class TestLookupField(OpenLookupChannel):
    model = TestModel
    plugin_options = {
        'render_in_input': True,
    }
```

The resulting webpage shows:
![res1](https://f.cloud.github.com/assets/1124536/1555751/3793c28c-4e80-11e3-8837-65be9dc7cdcc.png)

Instead of:
![res2](https://f.cloud.github.com/assets/1124536/1555752/3a571744-4e80-11e3-89be-3baed5acdd2e.png)