Add user mail logs to cataloger submissions

Our cataloguers cannot currently see the error output of any update submitted through BibEdit or Multi-edit. This pull requests aims to give them this information to more quickly respond to failures.

Granted, it may provide some spam for the users as well as it will also send e-mails upon completed submissions, and this could perhaps be solved at the BibUpload level to send to the offending user who created the task upon error?

What do you think?

@Osso @kaplun @jmartinm @fschwenn