fix deprecated warning with rake tasks

Author: pierrickrouxel

lib/arjdbc/railtie.rb

@@ -3,7 +3,7 @@
 module ArJdbc
   class Railtie < ::Rails::Railtie
     rake_tasks do
-      load File.expand_path('jdbc/rake_tasks.rb', File.dirname(__FILE__))
+      load File.expand_path('tasks.rb', File.dirname(__FILE__))
     end
   end
 end