Fixed all problems/warnings reported by "go vet"

app.go

@@ -51,7 +51,7 @@ func (a *App) Run(arguments []string) error {
 	context := NewContext(a, set, set)
 
 	if err != nil {
-		fmt.Println("Incorrect Usage.\n")
+		fmt.Printf("Incorrect Usage.\n\n")
 		ShowAppHelp(context)
 		fmt.Println("")
 		return err

app_test.go

@@ -14,7 +14,7 @@ func ExampleApp() {
 	app := cli.NewApp()
 	app.Name = "greet"
 	app.Flags = []cli.Flag{
-		cli.StringFlag{"name", "bob", "a name to say"},
+		cli.StringFlag{Name: "name", Value: "bob", Usage: "a name to say"},
 	}
 	app.Action = func(c *cli.Context) {
 		fmt.Printf("Hello %v\n", c.String("name"))
@@ -72,7 +72,7 @@ func TestApp_CommandWithArgBeforeFlags(t *testing.T) {
 	command := cli.Command{
 		Name: "cmd",
 		Flags: []cli.Flag{
-			cli.StringFlag{"option", "", "some option"},
+			cli.StringFlag{Name: "option", Value: "", Usage: "some option"},
 		},
 		Action: func(c *cli.Context) {
 			parsedOption = c.String("option")
@@ -96,8 +96,8 @@ func TestApp_ParseSliceFlags(t *testing.T) {
 	command := cli.Command{
 		Name: "cmd",
 		Flags: []cli.Flag{
-			cli.IntSliceFlag{"p", &cli.IntSlice{}, "set one or more ip addr"},
-			cli.StringSliceFlag{"ip", &cli.StringSlice{}, "set one or more ports to open"},
+			cli.IntSliceFlag{Name: "p", Value: &cli.IntSlice{}, Usage: "set one or more ip addr"},
+			cli.StringSliceFlag{Name: "ip", Value: &cli.StringSlice{}, Usage: "set one or more ports to open"},
 		},
 		Action: func(c *cli.Context) {
 			parsedIntSlice = c.IntSlice("p")

command.go

@@ -51,7 +51,7 @@ func (c Command) Run(ctx *Context) error {
 	}
 
 	if err != nil {
-		fmt.Println("Incorrect Usage.\n")
+		fmt.Printf("Incorrect Usage.\n\n")
 		ShowCommandHelp(ctx, c.Name)
 		fmt.Println("")
 		return err