Change browserid.org urls to persona.org, introduce static.login.persona.org for all static resources.

update wsapi_client to return errors in the standard node convention.  update all clients.  fix several areas in loadgen where we were not properly handling errors.  improve informational output of loadgen failures.  closes #838 - helps with issue #784 - closes #785

fix a bug in validation library.  if we find a parameter validation error, don't call the next handler in the onion ring, fail out

break 'checkParams' feature out into a separate file so it can be shared by multiple processes - issue #460