def self.from_omniauth(auth)
    where(provider: auth.provider, uid: auth.uid[username]).first_or_create do |user|
      user = User.new(username: params[username], provider: 'twitter'
      user.provider = auth.provider
      user.uid = auth.uid
      user.username = auth.info.nickname
      user.password = Devise.friendly_token[0,20]
      user.save(validate: false)
    end
  end