Handle response errors more properly

Value returned by http client Do function is nil or already closed if
there is any error. See
https://golang.org/src/net/http/client.go?s=16518:16570#L480
Therefore in order to avoid memory leaks in a potential ioutil.ReadAll
error and to be Go idioms compliant, the response body is deferred to be
closed immediately after checking there is no error with the Do function.

CAT: #fix
REF: #8
THX: @Zambiorix

Author: lion3ls

service/lambda/runtime/net/apigatewayproxy/server.go

@@ -144,13 +144,13 @@ func (s *Server) Handle(evt json.RawMessage, ctx *runtime.Context) (gwres *Respo
 		log.Println(err)
 		return
 	}
+	defer res.Body.Close()
 
 	body, err := ioutil.ReadAll(res.Body)
 	if err != nil {
 		log.Println(err)
 		return
 	}
-	res.Body.Close()
 
 	ct := res.Header.Get("Content-Type")
 	if ct == "" {