Add release:dir command

magefile.go

@@ -391,8 +391,14 @@ func (Release) Release() {
 
 }
 
-func (Release) Dirs() {
-
+// Creates all directories needed to release vikunja
+func (Release) Dirs() error {
+	for _, d := range []string{"binaries", "release", "zip"} {
+		if err := os.MkdirAll(RootPath+"/"+DIST+"/"+d, os.ModeDir); err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
 func (Release) Windows() {