Redmine

In my Redmin I want to sort my subproject according to a custom field (I called my new field "subproject priority").

How can I do ? Is there a way to custom the reports_controller.rb file or just better a existing plugin ?

My Redmine release :

Redmine version                2.5.0.stable
  Ruby version                   1.9.3-p551 (2014-11-13) [x86_64-linux]
  Rails version                  3.2.17
  Environment                    production
  Database adapter               Mysql2
Redmine plugins:
  no plugin installed