Manifest to install Opsmatic agent

The way to use the new class to install Opsmatic agent is:

    class { 'opsmatic::agent':
        token => $token,
        credentials => $debian_credentials,
    }

I suspect you likely want to subscribe to the Exec['opsmatic_agent_initial_configuration'] resource as well -- if for some reason the host_id file is removed, and then re-generated, you'd probably want the service to restart?