extract_authorization_code
Description:
Tries to extract an authorization code from a web page provided by the server.
 The function can be called multiple times, whenever the page load is finished. The default implementation uses 
      util_extract_from_uri to get the code from
      the given page_uri.
There can happen three states: 1) either the this cannot determine the authentication code from the page
      information, then the false is returned and the out_authorization_code is left untouched; or 2) the server reported a
      failure, in which case the function returns true and lefts the out_authorization_code untouched; or 3) the 
      this could extract the authentication code from the given arguments, then the function returns true
       and sets the received authorization code to out_authorization_code.
The page_content is null, unless flags returned by 
      get_flags contain also 
      EXTRACT_REQUIRES_PAGE_CONTENT.
This method is always called after get_authentication_policy.
Parameters:
| this | |
| source | an associated Source | 
| page_title | a web page title | 
| page_uri | a web page URI | 
| page_content | a web page content | 
| out_authorization_code | the extracted authorization code | 
Returns:
| whether could recognized successful or failed server response. The  |