omniauth-identity

intridea/omniauth-identity
https://github.com/intridea/omniauth-identity

#304 OmniAuth Identity - RailsCasts
http://railscasts.com/episodes/304-omniauth-identity?language=ja&view=asciicast

#241 Simple OmniAuth - RailsCasts
http://railscasts.com/episodes/241-simple-omniauth?language=ja&view=asciicast