tests: add test for IP address logging
tests: add test for IP address logging

Now that logging of remote IP addresses is working again, put it under
tests.

The tests check the output of `who` as long as the login messages for
successful and failed login attempts.

deryni/cockpit,cockpit-project/cockpit,deryni/cockpit,martinpitt/cockpit,garrett/cockpit,garrett/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpit-project/cockpit,deryni/cockpit,martinpitt/cockpit,deryni/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mvollmer/cockpit,garrett/cockpit,deryni/cockpit,mvollmer/cockpit,martinpitt/cockpit,garrett/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,deryni/cockpit,garrett/cockpit,deryni/cockpit,martinpitt/cockpit