Feature: Option to change operating system template

[jas8522]

Would be great to have the ability to change the OS template from within WHMCS Client Area (and admin area for that matter).

It would, of course, need to have serious data-loss warnings and verify with the user prior to accepting the change (like the reboot/shutdown buttons do now).

It should also search for the existence of a configurable option called "Operating System" and both use that to fill-out its dropdown with options and make sure to update the saved config option value in WHMCS (associated with the product) when the change has been submitted.