Fix inconsistent response parsing behaviour

- Change ResponseParser into utility functions (no more ctor)
- Only expect the XML string and not a reponse as the statusCode check
is performed by the request helper - reponseParser is now agnostic to
how the request is actually made.
Remove XML cruft from responses

- Standardise reponseparser.parse parameter order
- Push request error checking out of the parser back up to the caller
- Remove the xmlns attributes from the correct part of the reponse
- Remove one extra xmlnx:xsd property
0.10.0