Add comment and downtime tests

refs #5345
Add problem acknowledgement tests

refs #5345
Add change/modify attribute tests

refs #5345
Add tests for the delay of notifications

refs #5345
Add tests for disabling and scheduling active checks

refs #5345
Add test for SHUTDOWN_/RESTART_PROCESS

refs #5345
Add tests for the processing of passive check results

refs #5345
Add test for the PROCESS_FILE command

refs #5345
Add test for dispatching and dis-/enabling custom notifications

refs #5345
Add test for host-/servicegroup commands

refs #5345