_downsertBindings needs to clear the _subviews array

[DoomyTheFroomy]

The _upsertBindings function initialize on each call the _subviews array, based on the view.subviews. If you are using an ampersand-view-switcher for example to handle this kind of view, you will recognize that the _subiews array becomes bigger and bigger. This causes that the subviews are initialize and render more than once (eachampersand-view-switcher call).