Add Facebook login with Sorcery

The facebook key and secret defined in the sorcery config file are for
testing only and need to be changed and not committed to source when
app is ready to go live

app/controllers/oauths_controller.rb

@@ -0,0 +1,32 @@
+class OauthsController < ApplicationController
+  skip_before_filter :require_login
+
+  # sends the user on a trip to the provider,
+  # and after authorizing there back to the callback url.
+  def oauth
+    login_at(auth_params[:provider])
+  end
+
+  def callback
+    provider = auth_params[:provider]
+    if @user = login_from(provider)
+      redirect_to root_path, :notice => "Logged in with #{provider.titleize}!"
+    else
+      begin
+        @user = create_from(auth_params[:provider])
+
+        reset_session
+        auto_login(@user)
+        redirect_to root_path, :notice => "Signed up with #{provider.titleize}!"
+      rescue
+        redirect_to root_path, :alert => "Failed to login with #{provider.titleize}!"
+      end
+    end
+  end
+
+  private
+  def auth_params
+    params.permit(:code, :provider)
+  end
+
+end