differentiate receiving and publishing mqtt for the new json option in user_config.h

#318 so as to avoid user with non modified controllers to have regression on receiving (per default receiving is activated for both json and simple and prioritary analysed for json)

ZgatewayRFM69.ino

@@ -179,7 +179,7 @@ boolean RFM69toMQTT(void) {
   }
 }
 
-#ifdef simplePublishing
+#ifdef simpleReceiving
   void MQTTtoRFM69(char * topicOri, char * datacallback) {
     int loops;
     uint32_t startMillis;
@@ -228,7 +228,7 @@ boolean RFM69toMQTT(void) {
     }
   }
 #endif
-#ifdef jsonPublishing
+#ifdef jsonReceiving
   void MQTTtoRFM69(char * topicOri, JsonObject& RFM69data) {
   
    if (strcmp(topicOri,subjectMQTTtoRFM69) == 0){