It is an authentication application where user can be authenticated via. google account only. After successful login user can get all the google/gmail contacts.
GitHub URL: https://github.com/ripan/link
Register your project with https://code.google.com/apis/console
Set Hostname,Redirect URIs,Client id and Client secret in the following files
/config/initializers/omniauth.rb /config/initializers/omnicontacts.rb