Add support for displaying duplicates, disable fetching suggestions after accepting a suggestion

In cases where a typeahead matches on only part of an object or field, it may make sense to display duplicate results. For example, first and last names:

![untitled](https://f.cloud.github.com/assets/3845823/1322499/4c76d102-3432-11e3-81eb-e4386c98a21f.png)

When a suggestion is accepted, new suggestions aren't required (they should be identical) and old suggestions are obsolete, so I disabled fetching suggestions after selection and enabled clearing suggestions after selection.