Add support for PATCH method

@zachmullen I did a bit more digging and managed to find out how to get CherryPy to process the request body for a PATCH method ( an obscure configure option! ). We could use the same configuration option to enable the processing of DELETE bodies as well. I checked the HTTP spec. and there is nothing to say the a DELETE can't have a body ( or a GET for that matter, but that pretty messed up! )