Add LORA gateway

first implementation of a lora gateway integration, tested on ttgo heltec boards with embedded lora module #356
Sending and receiving working

lib/arduino-LoRa/examples/LoRaReceiver/LoRaReceiver.ino

@@ -0,0 +1,32 @@
+#include <SPI.h>
+#include <LoRa.h>
+
+void setup() {
+  Serial.begin(9600);
+  while (!Serial);
+
+  Serial.println("LoRa Receiver");
+
+  if (!LoRa.begin(915E6)) {
+    Serial.println("Starting LoRa failed!");
+    while (1);
+  }
+}
+
+void loop() {
+  // try to parse packet
+  int packetSize = LoRa.parsePacket();
+  if (packetSize) {
+    // received a packet
+    Serial.print("Received packet '");
+
+    // read packet
+    while (LoRa.available()) {
+      Serial.print((char)LoRa.read());
+    }
+
+    // print RSSI of packet
+    Serial.print("' with RSSI ");
+    Serial.println(LoRa.packetRssi());
+  }
+}