Revert "Use xn-howler"

This reverts commit e68196d184055f70b3963e77937f1134274ff876.
Introduce flux dispatcher and Howls store

Add a Flux dispatcher with three defined actions, appInit, newHowl, and
newHowlCreated.

Add a Howls store, which uses a Howls collection to store data.

Update New Howls view to dispatch the newHowl action in response to the
submit DOM event.  The Howls store responds to a newHowl action, and
creates a new howl in the store.  Upon success, the Howls store
dispatches a newHowlCreated action.  The New Howls view resets the new
howl input in response to the newHowlCreated action.