WEB-5211 - Common names check for agent on user

There was an exceedingly rare case where you could create a user from
the command-line then use that user to add a common name and it would
die because the user didn't have an agent. Silly, but easy enough to fix
(and friendlier for developers).
Fixed problem with data object spec

...The URL was invalid. ...Really, though, we should do a better job of
catching that for any URL. For this patch, though, it's fixing the only
failing error.