Handle update error

Signed-off-by: Lukas Bachschwell <lukas@lbsfilm.at>

main.go

@@ -20,7 +20,12 @@ func main() {
 		os.Exit(1)
 	} else if os.Args[1] == "upgrade" {
 		fmt.Print("Trying Upgrade... ")
-		update(gitTag)
+		err := update(gitTag)
+		if err != nil {
+			fmt.Println(err)
+		} else {
+			fmt.Println("Success")
+		}
 	} else if os.Args[1] == "version" {
 		fmt.Print("Version ")
 		fmt.Println(gitTag)