This might seem weird, but can we change the name to ```gaiagrid-collection-open```? The reason being is that we fire these events from a component into the window scope, so I think it's important that we follow strict namespacing. (Also it's inline with what we're doing elsewhere in the component).

See: https://github.com/EverythingMe/gaia/blob/master/shared/elements/gaia_grid/js/grid_dragdrop.js#L56