client: get_xml don't try to parse non-xml 5XX responses.
client: get_xml don't try to parse non-xml 5XX responses.


V1Server.get_xml method didn't handle properly if the query returned an
5XX error, which resulted in a double exception, when teh method tried
to parse the non-XML formatted response.

aarcro/VersionOne.SDK.Python,versionone/VersionOne.SDK.Python,doubleO8/versionone-sdk-spoon