restclient must be able to deal with multiple types of servers. Alter
the behavior of restclient.Result#Raw() to not process the body on
error, but instead to return the generic error (which still matches the
error checking cases in api/error like IsBadRequest). If the caller uses
.Error(), .Into(), or .Get(), try decoding the body as a Status.

For older servers, continue to default apiVersion "v1" when calling
restclient.Result#Error(). This was only for 1.1 servers and the
extensions group, which we have since fixed.

This removes a double decode of very large objects (like LIST).