FEATURE: optionally get extra profile info from facebook

This feature requires the application be approved by facebook, so it is
default off

db/migrate/20160919054014_add_fields_to_facebook_user_info.rb

@@ -0,0 +1,7 @@
+class AddFieldsToFacebookUserInfo < ActiveRecord::Migration
+  def change
+    add_column :facebook_user_infos, :about_me, :text
+    add_column :facebook_user_infos, :location, :string
+    add_column :facebook_user_infos, :website, :text
+  end
+end