title: Magento: Add images (or any attribute) to custom module
body: <p>I'm building a custom module and I need to be able to add an image to my data type much like we can add images to products. From what I learned, an image is simply an attribute.</p>
  
  <p>How do I add a tab to my module's edit page where the image upload functionality is provided and the uploaded images are automatically associated to my data type entries?</p>
  
  <p>Please note that I know how to add the tabs and even upload an image in plain PHP. I would just like to re-use the functionality that Products already have and do things the Magento way.</p>