Add SAMLv2 and ID-FFv1.2 helper methods, fix base url getter
Add SAMLv2 and ID-FFv1.2 helper methods, fix base url getter

 * add methods to return respones: return_idff12_response,
   return_idff12_request,

 * add get_base_path to retrieve the base URL for the IdP modules,
   modify metadata generating functions to use it.

incuna/authentic,incuna/authentic,pu239ppy/authentic2,BryceLohr/authentic,incuna/authentic,pu239ppy/authentic2,adieu/authentic2,adieu/authentic2,BryceLohr/authentic,adieu/authentic2,BryceLohr/authentic,incuna/authentic,BryceLohr/authentic,adieu/authentic2,pu239ppy/authentic2,pu239ppy/authentic2,incuna/authentic