Check user auth in api request

frontend/messages/en.json

@@ -65,6 +65,7 @@
     "project_name": "Project Name",
     "project_detail": "Project Detail",
     "public": "Public",
+    "private": "Private",
     "if_you_make_public": "If you make project public, everyone who has access to this site will be able to view it.",
     "close": "Close",
     "create": "Create",

frontend/messages/ja.json

@@ -64,6 +64,7 @@
     "project_name": "プロジェクト名",
     "project_detail": "プロジェクト詳細",
     "public": "パブリック",
+    "private": "プライベート",
     "if_you_make_public": "プロジェクトをパブリックにすると、このサイトにアクセスできるすべてのユーザーがプロジェクトを見ることができます。",
     "close": "閉じる",
     "create": "作成",