New strings to localization (#5225)

* error_can_not_delete_custom_field: Unable to delete custom field
* error_unable_to_connect: Unable to connect ({{value}})
* error_can_not_remove_role: This role is in use and can not be deleted.
* error_can_not_delete_tracker: This tracker contains issues and can't be deleted.


git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3627 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/roles_controller.rb

@@ -57,7 +57,7 @@ class RolesController < ApplicationController
     @role.destroy
     redirect_to :action => 'index'
   rescue
-    flash[:error] = 'This role is in use and can not be deleted.'
+    flash[:error] =  l(:error_can_not_remove_role)
     redirect_to :action => 'index'
   end