Merge attribute handling from request and response to commen code.

packages/ipp/urivalue.go

@@ -16,6 +16,10 @@ func NewUriValue(name, value string) *uriValue {
 	return u
 }
 
+func (u uriValue) Name() string {
+	return u.name
+}
+
 func (u uriValue) String() string {
 	return u.name + ":" + u.value
 }