Tidy ::applicationserver & ::applicationserver::pybal_check

* Move contents of ~pybal/.ssh/authorized_keys to a separate file.
* Use User & Group resources rather than Systemuser.
* Remove OS check from init.pp.
* One include per line.

Change-Id: I66e04d357200a1c785e34ce6b5fc7ddb1485f83a
Merge "Tidy ::applicationserver & ::applicationserver::pybal_check" into production