title: add attribute in product information -> Inventory tab
body: <p>Hey, I just realise how easy is to add attributes to the form products in ADMIN, and its working perfectly. 
  So similarly to setting attributes for General, Prices, Meta Information, Images, Recurring Profiles, Design and More Information, how can I add an attribute to Inventory form?</p>
  
  <p>Thanks in advance for any help.</p>