增加 before 與 after 方法

[Shishamou]

增加 before 與 after 讓程式碼更簡潔

const users = rest('/api/users');

users.options.before = () => {
  this.loading = true;
};

users.options.after = () => {
  this.loading = false;
};

# 個別設定
users.create.after = () => {
  this.closeDialog()
};