Fix ACN issue 436 for surfacing CNI errors to kubelet. (Azure#501)

Author: sathyasi

cni/network/network.go

@@ -382,7 +382,8 @@ func (plugin *netPlugin) Add(args *cniSkel.CmdArgs) error {
 if errConsAdd != nil {
 log.Printf("handleConsecutiveAdd failed with error %v", errConsAdd)
 result = resultConsAdd
-return errConsAdd
+err = errConsAdd
+return err
 }
 
 if resultConsAdd != nil {

cni/network/plugin/main.go

@@ -206,7 +206,7 @@ func main() {
 }
 
 if recover() != nil {
-return
+os.Exit(1)
 }
 }()