* Decouple role kubespray-defaults from download
Avoids doing re-importing the download role on every invocation of
kubespray-defaults (and skipping everything).
This has a measurable effect on playbook performance.
* Update docs refering to moved download defaults
The main functions are wrapped by a sys.exit function which expects and
argument. The curent implementation isn't returning values in all cases.
This change ensures main functions return a value in all cases.