Store fixes

This branch fixes a couple of issues with store-related dgrid modules (evidenced by DOH tests I've written, which I'll be submitting in another pull request momentarily).

It also adds the `dgrid-refresh-complete` event to Pagination, and modifies OnDemandList's implementation so that both match.  (This involved removing the `rows` property from the event in OnDemandList, because adding it to Pagination would've been kludgy at best, and it's possible to get a specific row via `grid.row(results[n])` anyway.)