title: Using git subtree for asset swapping
body: <p>I'm working on an Android project which has several skins/graphics packs.
  I have created several folders of assets which are named identically, but are different graphics (for different brands).</p>
  
  <p>Initially I thought that I could create a main project which includes all source code, and then just create a subtree for each brand, containing the different assets. I have had issues though, adding the subtree to the original project.</p>
  
  <p>How should I setup a working git main project and different assets subtrees?</p>