title: How to add a product variant with the Ruby gem
body: <p>What is the correct way to add a product variant? </p>
  
  <p>I create the product successfully and it shows up in my Shopify admin. However the price is always zero and the quantity is always infinity.</p>
  
  <p>I've tried creating a variant with inventory_quantity and price set, as well as with product_id set in prefix_options.</p>
  
  <p>However admin is always showing price zero and quantity infinity.</p>
  
  <pre><code>Rails v3.2.5
  shopify_api v3.0.0
  shop name: vacation-2
  </code></pre>
  
  <p>I don't get errors doing the API calls. I simply don't see my variant data in the product in admin.</p>