Call ksinstall_rpm with the correct arguments.

The first argument (and package) was being consumed as a $config.

The function doesn't use $config anymore, but is exported by hooks and
we mustn't change the API.
Disable some repositories while Yum is not ready
Document the disabled_repos field.
Fix the header of the ks generator
Merge pull request #25 from piojo/fix-ksinstall

Disable some repositories during the %post phase