尝试使用Yelp身份验证启动Rails服务器时，出现此错误：
/var/lib/gems/1.9.1/gems/omniauth-1.2.1/lib/omniauth/builder.rb:50:in `rescue in provider': Could not find matching strategy for :yelp. You may need to install an additional gem (such as omniauth-yelp). (LoadError)
但是，在我的gemfile中，我有一行
gem 'omniauth-yelp'
跑了
bundle install
在config / initializers / omniauth.rb中，有一行
provider :yelp, ENV['yelp_consumer_key'], ENV['yelp_consumer_secret']
为什么我的应用程序没有注意到安装了omniauth-yelp？