Allow users to override the owner group

[ni-fgenois]

I'm experiencing some problems on Mac when the owner user doesn't have any associated groups with the same name:

TASK [staticdev.pyenv : Copy over check-configure-options.py] *************************************************************************************************************************************************************************************************
task path: /mnt/c/code/ansible-izo/ansible_roles/staticdev.pyenv/tasks/custom_facts.yml:7
fatal: [izo-sts-mac-02]: FAILED! => {"changed": false, "checksum": "8832f3169e82c52f2462e0fcee26f8eb496ec35a", "gid": 0, "group": "wheel", "mode": "0644", "msg": "chgrp failed: failed to look up group MY_USER", "owner": "MY_USER", "path": "/etc/ansible/facts.d/check-configure-options.py", "size": 194, "state": "file", "uid": 502}

Nice module btw :)