When sending na IQ we need the resulting iq only when its type is 'result' or 'error'.

When sending an IQ we need the resulting iq only when its type is 'result' or 'error'. Fixes a problem where it is possible server to use the same id to send us an iq packet with type 'get' and Strophe crashes with error 'Strophe: error: Got bad IQ type of get undefined'.