Extend the setup wizard to allow choosing whether to load the sample data or not

Currently, when seven cogs is deployed (such as in the default bundle) the data is always loaded. It would be very useful to add an option to the setup wizard to let the user decide whether the default data from seven cogs should be loaded or not. That way a lot of time would be saved to the administrators who forget to remove the seven cogs WAR before loading the portal for the first time.

That option should only be shown when the setup wizard hook is installed (which will require designing some detection system that works across all app servers).

It would be nice if the system is extensible so that it could detect several hooks that are able to load data and let the user choose which one should be loaded and which should not.