* Make the module_utils path configurable
* Add a config value to define the path site module_utils files
* Handle module_utils that do not have source as an error
* Make an integration test for module_utils envvar working
* Add documentation for the ANSIBLE_MODULE_UTILS config option/envvar
* Add it to the sample ansible.cfg
* Add it to intro_configuration.
* Also modify intro_configuration to place envvars on equal footing with
the config options (will need to document the envvar names in the
future)
* Also add the ANSIBLE_LIBRARY use case from
https://github.com/ansible/ansible/issues/15432 so we can close out
that bug.
