Added isVisitor, isAdmin, and isRegistered methods to User object instead

of hard coding checks everywhere with group ids. And updated the code base 
   to match.

lib/WebGUI/Workflow/Activity/SendNewsletters.pm

@@ -86,7 +86,7 @@ sub execute {
         # get user object
         $eh->info("Getting user $userId");
         my $user = WebGUI::User->new($self->session, $userId);
-        next if ($user->userId eq "1");
+        next if ($user->isVisitor);
         my $emailAddress = $user->profileField("email");
         next if ($emailAddress eq "");