Test server can access WPJobManager.com for updates

wpjm-update-access-test.php

<?php
/**
 * Plugin Name: WP Job Manager - Update access tester
 * Description: Pings our site to see if your server can connect. Just head to <a href="/?wpjm-test=1">yoursite.com/?wpjm-test=1</a> whilst logged in as admin.
 * Version: 1.0.0
 * Author: Mike Jolley
 * Requires at least: 4.1
 * Tested up to: 4.3
 */
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

add_action( 'wp_loaded', 'wpjm_update_access_tester' );

function wpjm_update_access_tester() {
	if ( ! empty( $_GET['wpjm-test'] ) && current_user_can( 'manage_options' ) ) {
	  $response = wp_safe_remote_get( 'https://wpjobmanager.com' );

	  if ( ! is_wp_error( $response ) ) {
	  	wp_die( 'SUCCESS' );
	  } else {
	  	wp_die( 'FAIL - ' . $response->get_error_message() );
	  }
	}
}