FEATURE: single sign on support

Added support for outsourcing auth to a different website, documentation on meta

db/migrate/20140224232913_add_single_sign_on_records.rb

@@ -0,0 +1,12 @@
+class AddSingleSignOnRecords < ActiveRecord::Migration
+  def change
+    create_table :single_sign_on_records do |t|
+      t.integer :user_id, null: false
+      t.string :external_id, null: false, length: 255
+      t.text :last_payload, null: false
+      t.timestamps
+    end
+
+    add_index :single_sign_on_records, :external_id, unique: true
+  end
+end