Make sure to preserve inherited return value from refresh
OnDemandList: reject refresh promise even if a sync error occurs
Pagination: make sure to clean up listeners
Pagination: warn about no store instead of throwing; fixes #355
Pagination: simplify _onNotification logic

This removes a special case that was initially added for if an item was
removed from the last page.  The thing is, we have no idea if that item
was in fact added to a previous page, in which case the result would be
to actually shift all preceding items in the last page down by one,
warranting a re-render of the page anyway.
Pagination: make gotoPage (and by extension, refresh) return promise
OnDemandList: fix _trackError callback so async errors are emitted
Pagination: simple tweak to make return value to _trackError consistent
Refactor OnDemand.html and expand Pagination.html tests