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/LoRaSender/LoRaSender.ino

@@ -0,0 +1,31 @@
+#include <SPI.h>
+#include <LoRa.h>
+
+int counter = 0;
+
+void setup() {
+  Serial.begin(9600);
+  while (!Serial);
+
+  Serial.println("LoRa Sender");
+
+  if (!LoRa.begin(915E6)) {
+    Serial.println("Starting LoRa failed!");
+    while (1);
+  }
+}
+
+void loop() {
+  Serial.print("Sending packet: ");
+  Serial.println(counter);
+
+  // send packet
+  LoRa.beginPacket();
+  LoRa.print("hello ");
+  LoRa.print(counter);
+  LoRa.endPacket();
+
+  counter++;
+
+  delay(5000);
+}