Accept all 2xx codes, not *just* 200
Accept all 2xx codes, not *just* 200

/cc @tunam3lt
allen-zeng/PromiseKit,mxcl/PromiseKit,pgherveou/PromiseKit,allen-zeng/PromiseKit,mxcl/PromiseKit,mxcl/PromiseKit,pgherveou/PromiseKit,pgherveou/PromiseKit