Skip unknown usernames rather than print "<unknown>".

Not sure what the original motivation for printing <unknown> was (it
shouldn't ever come up in normal operation, only if something weird
happens like we manually unset a user's username in the database). But
it's now rather inconvenient because we don't yet clean up deleted
organizations from a site, so you would see <unknown> for every
authorized organization that has been deleted. While we should
eventually clean up deleted organizations from a site's
"authorized_orgs" field, for now this will clean up the output of this
command.

tools/deploy.js

@@ -631,9 +631,7 @@ var listAuthorized = function (site) {
 
     process.stdout.write((auth.loggedInUsername() || "<you>") + "\n");
     _.each(info.authorized, function (username) {
-      if (! username)
-        process.stdout.write("<unknown>" + "\n");
-      else
+      if (username)
         process.stdout.write(username + "\n");
     });
     return 0;