## auth method
#
  def User.authenticate(*args)
    options = args.extract_options!.to_options!
    email = args.shift || options[:email]
    password = args.shift || options[:password]

    return nil if email.blank?

    user = User.where(:email => email.strip.downcase).first

    return nil if user.blank?
    return nil if user.password.blank?

    user.password == password ? user : false
  end