some basic tests for admin/users controller, fixed bug in admin/users controller for displaying users

Fixes by hounci violations

spec/factories/roles.rb

@@ -0,0 +1,16 @@
+FactoryGirl.define do
+  factory :role do
+
+    factory :admin_role do
+      name 'Admin'
+    end
+
+    factory :organizer_role do
+      name 'Organizer'
+    end
+
+    factory :participant_role do
+      name 'Participant'
+    end
+  end
+end