Add smartConfig support (#136)

* smartConfig support

* fixed bug, added example

* added _smartConfigDone = ture

* changed example name, added explanation

libraries/WiFi/examples/WiFiSmartConfig/WiFiSmartConfig.ino

@@ -0,0 +1,36 @@
+#include "WiFi.h"
+
+void setup() {
+  Serial.begin(115200);
+
+  //Init WiFi as Station, start SmartConfig
+  WiFi.mode(WIFI_AP_STA);
+  WiFi.beginSmartConfig();
+
+  //Wait for SmartConfig packet from mobile
+  Serial.println("Waiting for SmartConfig.");
+  while (!WiFi.smartConfigDone()) {
+    delay(500);
+    Serial.print(".");
+  }
+
+  Serial.println("");
+  Serial.println("SmartConfig received.");
+
+  //Wait for WiFi to connect to AP
+  Serial.println("Waiting for WiFi");
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+
+  Serial.println("WiFi Connected.");
+
+  Serial.print("IP Address: ");
+  Serial.println(WiFi.localIP());
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+
+}