title: How to recover deleted build definition
body: <p>We are using the "new, scriptable build system" of TFS 2015 and all of a sudden one of our build definitions is gone. It seems that it deleted itself.</p>
  
  <p>Is there a way to undelete/recover a build definition?</p>
  
  <p>Where are the build definitions (those JSON files) acutally stored?</p>