Make CLI functions return error instead of fatal out (#1379)

Before this PR, CLI functions fatal out when encountering error
instead of returning it. Such behavior makes it hard to reuse 
the functions nor writing unit tests. This PR aims to make functions 
return errors instead of error out.

pkg/fission-cli/cmd/support/resources/resource.go

@@ -24,7 +24,7 @@ import (
 	"github.com/ghodss/yaml"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
-	"github.com/fission/fission/pkg/fission-cli/log"
+	"github.com/fission/fission/pkg/fission-cli/consolemsg"
 	"github.com/fission/fission/pkg/utils"
 )
 
@@ -45,7 +45,7 @@ func getPodFileName(dumpdir string, pod metav1.ObjectMeta, containerName string)
 func writeToFile(file string, obj interface{}) {
 	bs, err := yaml.Marshal(obj)
 	if err != nil {
-		log.Info(fmt.Sprintf("Error encoding object: %v", err))
+		consolemsg.Info(fmt.Sprintf("Error encoding object: %v", err))
 		return
 	}
 
@@ -57,6 +57,6 @@ func writeToFile(file string, obj interface{}) {
 
 	err = ioutil.WriteFile(file, bs, 0644)
 	if err != nil {
-		log.Info(fmt.Sprintf("Error writing file %v: %v", file, err))
+		consolemsg.Info(fmt.Sprintf("Error writing file %v: %v", file, err))
 	}
 }