broadcast both submitter and owner to fedmsg

Back in commit 1a4473e7a4dc1adbff5868ae0395625bef78d17a, a change was
introduced that changed the 'user' field in fedmsg represent the person who
kicked off a build instead of the person who owned the particular copr.
This broke code in other fedmsg consumers that tried to build links from
that user field to https://copr.fedoraproject.org/$USER/$COPR

This change re-introduces the copr owner's username to the message.