no_results_fallback_option_index

Gives possibility to have one `<option>` from the original `<select>` chosen as a fallback default. 

If the user filters out all other `<option>`s, then this `<option>` will remain selected and highlighted. On `blur`, it will remain selected. 

Particularly useful for cases where a value is required and "Other" is valid `<option>`.

![chosen-no_options_fallback](https://cloud.githubusercontent.com/assets/4896806/2655163/ec7b8ff4-bfe1-11e3-87ac-803b01659eb9.png)