Execute Action at monitoring server failure.(deal with Issu 251)

Add a mechanism to do the action, when detected of the monitoring server failure (e.g. doesn't reply).

When Arm thread initializ, register trriger and monitoring server info to chashDB(sqlite).
when a failure was detected, Update the trigger and Register the event, and to perform the action(if registration).
TriggerID / Message Comment is a provisional value.

please confirm and comment.
'before' is not adjective. So this variable name 'beforeFailureStatus' seems unnatural.
In this case, 'previous' is often used.