make pod termination grace period configurable

pkg/util/config/config.go

@@ -63,6 +63,8 @@ type Config struct {
 	Workers              uint32         `name:"workers" default:"4"`
 	APIPort              int            `name:"api_port" default:"8080"`
 	RingLogLines         int            `name:"ring_log_lines" default:"100"`
+
+	PodTerminateGracePeriod time.Duration `name:"pod_terminate_grace_period" default:"5m"`
 }
 
 // MustMarshal marshals the config or panics