Using correct service manager to handle goagents.

[cnatan]

Forced the "service" service manager in service module through "use" argument.
The service module actually uses system specific modules, it uses the value of the 'ansible_service_mgr'. In RHEL 7.2 this means 'systemd' which ignore the /etc/init.d/go-agent? scripts. Forcing the "service" option must work on every OS.

This bug caused to task "Ensure Go-agents are not running yet (waiting for server config), but are enabled on startup." to always fail in RHEL 7.2.

[ghost]

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