Site#parse no longer depends on SiteConfigResponse
Site#parse no longer depends on SiteConfigResponse

Remove absolute xpath expectation, so that XML can be parsed if pulled
in from other places (such as exporting Site#to_xml).

tomhart-r7/nexpose-client,rapid7/nexpose-client,jhart-r7/nexpose-client,nbirnel/nexpose-client,gschneider-r7/nexpose-client