add stub for help

containers.go

@@ -57,7 +57,7 @@ func (x *ContainersCommand) Execute(args []string) error {
 
 		clientContainers, err := client.ListContainers(docker.ListContainersOptions{All: true})
 		if err != nil {
-			return err
+			return fmt.Errorf("Unable to connect: %s\nFor help, run 'dockviz help'", err)
 		}
 
 		var conts []Container

help.go

@@ -0,0 +1,22 @@
+package main
+
+import "fmt"
+
+type HelpCommand struct {
+	// nothing yet
+}
+
+var helpCommand HelpCommand
+
+func (x *HelpCommand) Execute(args []string) error {
+	fmt.Println("stub help is here")
+
+	return nil
+}
+
+func init() {
+	parser.AddCommand("help",
+		"Help for this tool.",
+		"",
+		&helpCommand)
+}

images.go

@@ -59,7 +59,7 @@ func (x *ImagesCommand) Execute(args []string) error {
 
 		clientImages, err := client.ListImages(docker.ListImagesOptions{All: true})
 		if err != nil {
-			return err
+			return fmt.Errorf("Unable to connect: %s\nFor help, run 'dockviz help'", err)
 		}
 
 		var ims []Image