title: Android Studio can't find custom sdk
body: <p>My company uses a customized flavor of API 18 called (-18) and we're making the transition from Eclipse to Android Studio. When my gradle tries to sync I get the error message, "Failed to find target with hash string 'android-18-cnh' in C:\Android\sdk" I open my SDK manager and get this:</p>
  
  <p><a href="https://i.stack.imgur.com/yxoRx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yxoRx.png" alt="enter image description here"></a></p>
  
  <p>I haven't been able to find anyone who has experienced this same problem. Here's what my standalone SDK manager looks like. Seems to recognize the custom api flavor so not sure what's going on. This custom api works perfectly fine in eclipse.</p>
  
  <p>Standalone SDK Manager:
  <a href="https://i.stack.imgur.com/P8hoZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/P8hoZ.png" alt="enter image description here"></a></p>