-added a "getValOrDefault" convenience function and calls for optionally specifying some currently hardcoded values (unstable_restarts_monitor_period, max_allowed_unstable_restarts)
-fixed bug where clu.pm2_env.min_uptime custom config value was never being used
-added a hook to call an external function with exit details (path, id, exit code, numRestarts, is the app being stopped for good)