You can already see that they have added the kit system because when you join a game it says 'Do /sw kit (Kit name) to choose a kit'. However when you do that command there are no kits yet, so the system is added but the kits need to be made.
They have not "added" that, this comes default in the plugin. @drtshock does not make all the plugins for minetime, the majority of the plugins are not made by him.