Add examples network time request

examples/getNetworkTime/getNetworkTime.ino

@@ -0,0 +1,36 @@
+#include "IoTtweetNBIoT.h"
+
+String userid = "your-iottweet-account-id";       /*IoTtweet account user ID (6 digits, included zero pre-fix)*/
+String key = "your-device-key";                   /*IoTtweet registered device key in "MY IOT Garage"*/
+float data0, data1, data2, data3;                 /*Your sending data variable.*/
+String private_tweet = "Request network time";              /*Your private tweet meassage to dashboard*/
+String public_tweet = "Hello IoTtweet";           /*Your public tweet message to dashboard*/
+
+const long looptime_task1 = 5;                         /* Task 1 time in sec. */
+
+unsigned long previousMillis_task1 = 0;
+
+IoTtweetNBIoT myNBiot;
+
+void setup(){ 
+
+  myNBiot.init();
+  previousMillis_task1 = millis();
+
+}
+void loop(){ 
+
+  unsigned long currentMillis_task1 = millis();
+
+  /* Task 1 */
+  if (currentMillis_task1 - previousMillis_task1 >= looptime_task1*1000)
+    { 
+
+      /* Request network time */
+      String nt = myNBiot.getNetworkTime();
+      Serial.println("Network time is " + nt);
+
+      previousMillis_task1 = currentMillis_task1;
+    }
+
+}