Ataki/gridfs

@stvstnfrd to review commit
I'm concerned with unintended consequences of placing this here. It
looks like this script will be included (and attach the event listener)
on _every_ studio page. I worry that this notification could then be
unintentionally triggered by previously existing, uncaught upload
errors. I'm not sure how likely this case is, but it is something that
we'd want to investigate. Generally speaking, the wider the scope of a
change, the more effort is required when submitting it upstream.

I wonder if there's a more localized place for this. Could we create and
show the `NotificationView.Error` directly, instead of triggering the
Backbone event.

Thoughts?