Add support for Facebook authentication

test/fixtures/users.yml

@@ -262,3 +262,17 @@ google_user:
   terms_agreed: "2010-01-01 11:22:33"
   terms_seen: true
   languages: en
+
+facebook_user:
+  id: 20
+  email: facebook-user@example.com
+  status: active
+  pass_crypt: <%= Digest::MD5.hexdigest('test') %>
+  creation_time: "2008-05-01 01:23:45"
+  display_name: facebookuser
+  data_public: true
+  auth_provider: facebook
+  auth_uid: 123456789
+  terms_agreed: "2010-01-01 11:22:33"
+  terms_seen: true
+  languages: en