title: add product to cart in woocommerce from outside Wordpress
body: <p>i've figured out that is possible to add a product to cart with these lines:</p>
  
  <p><code>global $woocommerce;
  $woocommerce-&gt;cart-&gt;add_to_cart($product_id);</code></p>
  
  <p>My question is, how to add a product to cart from outside? I have a simple php site, just want to delegate the sales to wordpress/woocommerce. 
  Can i do it with the Api?
  Can you point me in th right direction?</p>