This change is in response to issue #1515.
Original pull request #1580.
The original problem is: in authorized_key module you have no idea about users
which will be created by Ansible at first run. I can propose next two ways to
solve this problem:
1. Combine modules system/user.py and system/authorized_key.py in one module
(so you will know everything about users in that module)
2. Use small workaround: add my commit and always provide 'path' parameter
for authorized_key module during runs with --check option.
ac40d9f41a