title: omniauth with facebook not working on production
body: <p>i'm working with omniauth in my rails app, i have sign with facebook and twitter button, when i'm putting in facebook in the site url filed localhost:3000, all is working, but when i'm uploading the site to heroku and changing in the site url to sitename.heroku.com, the twiiter login button working but the facebook button don't working...</p>