ROLLBACK: Fixed building XML dynamic schemas

Ignore-this: d55fff6f19834393a295b93b054d4e7f

rolling back:

Tue Sep 18 10:56:18 CEST 2012  Saul Ibarra <saul@ag-projects.com>
  * Fixed building XML dynamic schemas

  If path is not fully specified fails on Windows

    M ./sipsimple/payloads/__init__.py -1 +2

darcs-hash:20120921134837-56b4d-d8499175da5ced889e9d1c1022dff2592e88a1a5
Allow extra headers to be passed to Registration

Ignore-this: 3fac5abf63cb8292a2a1172c65cc839c

darcs-hash:20121001100816-56b4d-090d12da51be5e88604a7366b8dedf8ea38705f8