Change cache file owner, group and mode.

* Use `puppet:puppet` as default user/group
* Use 0750 as default cache file mode
* Change cache file ownership for every saved file

* Refactor creating cache files into separate function.
Merge pull request #2 from siminm-nextdoor/master

Change cache file owner, group and mode.
Don't log the secret value
When debug is on, log what fqdn/secret requests
Remove unused require
Merge pull request #3 from cmclaughlin/master

Don't log secret values, debug option for logging what servers request what secrets