Added Github authentication option, disabled by default with enable options in settings.

db/migrate/20130226015336_add_github_user_info.rb

@@ -0,0 +1,13 @@
+class AddGithubUserInfo < ActiveRecord::Migration
+  def change
+    create_table :github_user_infos do  |t| 
+      t.integer :user_id, :null => false
+      t.string :screen_name, :null => false
+      t.integer :github_user_id, :null => false
+      t.timestamps 
+    end
+    
+    add_index :github_user_infos, [:github_user_id], :unique => true
+    add_index :github_user_infos, [:user_id], :unique => true
+  end
+end