Include normalized prefix results in has search

[yossariano]

• It seems the matching with ngrams is excluding certain small-enough matches such as N.Y. This changes makes it so we're also always checking normalized keyword results so that the results of a has search will always contain at least the results of a starts_with search for preferredTerm.
• Tested with http://localhost:8082/api/v0.1/discovery/browse/subjects?q=New%20York%20(N%2EY%2E)%20--%20Historical%20geography&search_scope=has as an example for before (no results) and after (4 results)

[charmingduchess]

looks good!