(android) added method for getting BSSID

Author: Corey Wilson

android/src/main/java/com/pusherman/networkinfo/RNNetworkInfo.java

@@ -44,6 +44,11 @@ public void getSSID(final Callback callback) {
     callback.invoke(ssid);
   }
 
+  @ReactMethod
+  public void getBSSID(final Callback callback) {
+    callback.invoke(wifi.getConnectionInfo().getBSSID());
+  }
+
   @ReactMethod
   public void getIPAddress(final Callback callback) {
     String ipAddress = null;