Make a GET request for url and return whatever content we get

def raw(self, url, extra_headers=None, params=None):
        'Make a GET request for url and return whatever content we get'
        r = self.request(url, extra_headers=extra_headers, params=params)
        # uncomment to dump raw xml
#         with open('/tmp/%s.xml' % time.time(), 'wb') as f:
#             f.write(r.content)

        if not r.ok:
            o = lxml.objectify.fromstring(r.content)
            JFSError.raiseError(o, url)
        return r.content