Send the submitter email when publishing concludes

[jeffhhk]

Now that the "Done Uploading" HTTP request is short (see #51), we have another small UI issue. The issue is that the user now has a hard time finding out when the fileset either becomes available or fails in processing.

This is suggestion 2 of 2 for how to let the user know what happened with their submissions.

When publishing concludes, the submitter probably wants to know. You collected the submitter's email upon registration. So send them an email indicating success or failure.