Use zero as default Keep Alive

Author: jjok

src/Connector.php

@@ -122,7 +122,7 @@ private function listenForPackets(Stream $stream)
     private function keepAlive(Stream $stream, $keepAlive)
     {
         if($keepAlive > 0) {
-            $interval = (int) ($keepAlive / 2);
+            $interval = $keepAlive / 2;
 
             $this->getLoop()->addPeriodicTimer($interval, function(Timer $timer) use ($stream) {
                 $packet = new PingRequest($this->version);

src/packet/Connect.php

@@ -64,8 +64,7 @@ public function __construct(
         $willMessage = null,
         $willQos = null,
         $willRetain = null,
-//        $keepAlive = 0
-        $keepAlive = 10
+        $keepAlive = 0
     ) {
         parent::__construct($version);
         $this->clientId = $clientId;

src/packet/ConnectionOptions.php

@@ -107,8 +107,7 @@ class ConnectionOptions
      *
      * @var int
      */
-//    public $keepAlive = 0;
-    public $keepAlive = 10;
+    public $keepAlive = 0;
 
     /**
      * ConnectionOptions constructor.