Adds a css class (overdue) to overdue issues on issue lists and detail views (#2337).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@2140 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/issue.rb

@@ -195,6 +195,11 @@ class Issue < ActiveRecord::Base
     self.status.is_closed?
   end
   
+  # Returns true if the issue is overdue
+  def overdue?
+    !due_date.nil? && (due_date < Date.today)
+  end
+  
   # Users the issue can be assigned to
   def assignable_users
     project.assignable_users