Adjusting SsoHandlerClass JavaScript to match SSO

See documentation at http://docs.webplatform.org/wiki/WPD:Projects/SSO/How_we_implemented_it#JavaScript_shared_module:_Detect_and_start_automatically_a_session

Change-Id: Ica7f9c53487172dd96c177a8137193eff48f947c
Refactoring library behavior

* Can declare config before initializing
* Can post messages manually (temporary?)

Change-Id: Ic0185e09268e1f17f34e6517c7c582c46cd01f56