Unload logic for generic and keyphrase sound models.

 When delete is called, now the STH unloads the corresponding models.

Fix bug with keyphrase where a delete call didn't unload (or stop)
the keyphrase model.

Bug: 27279380
Change-Id: Ia34f713d2aecef4102c0f0ccc57b8d2e5febe4bb
6 files changed