Refactor structure, use cobra

pkg/utils/ensure.go

@@ -0,0 +1,15 @@
+package utils
+
+import "os"
+
+func EnsureDirExists(dirName string) error {
+	if _, err := os.Stat(dirName); os.IsNotExist(err) {
+		err := os.Mkdir(dirName, 0755)
+		if err != nil {
+			return err
+		}
+	} else if err != nil {
+		return err
+	}
+	return nil
+}