Ensure WiFi.localIP() is converted to a string when needed. (#455)

Due to a potential compiler issue (e.g. Platformio vs. Arduino IDE) it
seems that WiFi.localIP() wasn't being automatically associated with the
string varient when used in a string context.
Forcing the conversion should fix it in all cases.

Fixes #452

Checked by @DiggiD

examples/IRGCTCPServer/IRGCTCPServer.ino

@@ -111,7 +111,7 @@ void setup() {
 
   server.begin();
   IPAddress myAddress = WiFi.localIP();
-  Serial.println(myAddress);
+  Serial.println(myAddress.toString());
   irsend.begin();
 }
 

examples/IRMQTTServer/IRMQTTServer.ino

@@ -804,7 +804,7 @@ void setup_wifi() {
     delay(5000);
   }
 
-  debug("WiFi connected. IP address: " + WiFi.localIP());
+  debug("WiFi connected. IP address: " + WiFi.localIP().toString());
 }
 
 void setup(void) {

examples/IRServer/IRServer.ino

@@ -102,7 +102,7 @@ void setup(void) {
   Serial.print("Connected to ");
   Serial.println(ssid);
   Serial.print("IP address: ");
-  Serial.println(WiFi.localIP());
+  Serial.println(WiFi.localIP().toString());
 
   if (mdns.begin("esp8266", WiFi.localIP())) {
     Serial.println("MDNS responder started");