fix system stack error

* JournalMethods is included multiple times, which triggers the #included? callback on line 68 multiple times, with triggers #alias_method_chain on line 72 multiple times, which will end up in an infinite loop: #user_with_name= is the very same method as #user_without_name=

lib/plugins/acts_as_journalized/lib/redmine/acts/journalized/users.rb

@@ -41,7 +41,7 @@ module Redmine::Acts::Journalized
   # responsible for the associated update to the parent.
   module Users
     def self.included(base) # :nodoc:
-      Journal.send(:include, JournalMethods)
+      Journal.send(:include, JournalMethods) unless Journal.include? JournalMethods
 
       base.class_eval do
         include InstanceMethods
@@ -68,7 +68,7 @@ module Redmine::Acts::Journalized
       def self.included(base) # :nodoc:
         base.class_eval do
           belongs_to :user
-         # attr_protected :user_id
+          # attr_protected :user_id
           alias_method_chain :user=, :name
         end
       end