GetJournalEditServlet should check requestor principal against NameNode principal pattern

At my employer (HubSpot), we found it difficult to provide our JournalNodes with configurations that enumerate the exact principals that their counterpart NameNodes will have. Many situations in Hadoop that check requestor principal names allow a glob pattern so that exact names do not need to be known ahead of time. We applied a similar logic in GetJournalEditServlet successfully. I'd like to contribute this change upstream.