help with push.js

<?php
include('is_logged.php');//Archivo verifica que el usario que intenta acceder a la URL esta logueado
// checking for minimum PHP version
if (version_compare(PHP_VERSION, '5.3.7', '<')) {
    exit("Sorry, Simple PHP Login does not run on a PHP version smaller than 5.3.7 !");
} else if (version_compare(PHP_VERSION, '5.5.0', '<')) {
    // if you are using PHP 5.3 or PHP 5.4 you have to include the password_api_compatibility_library.php
    // (this library adds the PHP 5.5 password hashing functions to older versions of PHP)

}		
		if (empty($_POST['incidencia'])){
			$errors[] = "Por favor seleccione una incidencia";
		} elseif (empty($_POST['tema'])){
			$errors[] = "Tema vacío";
		}  elseif (empty($_POST['detalle'])) {
            $errors[] = "detalle vacío";
        } elseif (empty($_FILES['imagen']['name'])) {
		    $errors[] = "imagen vacía";
        }  elseif (
			!empty($_POST['incidencia'])
            && !empty($_POST['tema'])
			&& !empty($_POST['detalle'])
            && !empty($_FILES['imagen'])
        )  {
            require_once ("../config/db.php");
			require_once ("../config/conexion.php");
			
				
                $incidencia = mysqli_real_escape_string($con,(strip_tags($_POST["incidencia"],ENT_QUOTES)));
				$tema = mysqli_real_escape_string($con,(strip_tags($_POST["tema"],ENT_QUOTES)));
				$detalle = mysqli_real_escape_string($con,(strip_tags($_POST["detalle"],ENT_QUOTES)));
                $imagen = ($_FILES['imagen']);
                $firstname = mysqli_real_escape_string($con,(strip_tags($_POST["firstname"],ENT_QUOTES)));
                $sql = "SELECT * FROM ticket WHERE incidencia = '" . $incidencia . "' OR tema = '" . $tema . "';";
                $query_check_incidencia = mysqli_query($con,$sql);
				
                    $sql = "INSERT INTO ticket (incidencia, tema, detalle, firstname, imagen)
                            VALUES('".$incidencia."','".$tema."','" . $detalle . "','".$_SESSION['firstname']."','" . $_FILES['imagen']['name'] . "');";
           
                    $query_new_incidencia_insert = mysqli_query($con,$sql);
$imagen = $_FILES['imagen']['name']; 
                    $ruta_tmp = $_FILES['imagen']['tmp_name'];
					$ruta_final = '../img/' . $imagen; 
                    if (!file_exists($ruta_final)) {
                    move_uploaded_file($ruta_tmp, $ruta_final);
        }
		}
            
         else {
            $errors[] = "Un error desconocido ocurrió.";
        }
		
		if (isset($errors)){
			
			?>
			<div class="alert alert-danger" role="alert">
				<button type="button" class="close" data-dismiss="alert">&times;</button>
					<strong>Error!</strong> 
					<?php
						foreach ($errors as $error) {
								echo $error;
							}
						?>
			</div>
			<?php
			}
			if (isset($messages)){
				
				?>
				<div class="alert alert-success" role="alert">
						<button type="button" class="close" data-dismiss="alert">&times;</button>
						<strong>¡Bien hecho!</strong>
						<?php
							foreach ($messages as $message) {
									echo $message;
								}
							?>
				</div>
				<?php
               
			}

?>

<script type="text/javascript" src="push.js-master/src/push/Push.js">
    </script>
    <script>
Push.create("Hello world!", {
    body: "How's it hangin'?",
    icon: '/icon.png',
    timeout: 4000,
    onClick: function () {
        window.focus();
        this.close();
    }
});
</script>