title: Trigger builds based on TFS workitem information
body: <p>I am currently looking for best practices to implement as use case in VSTS</p>
  
  <p>Details below</p>
  
  <p>1) Our board has several tfs work items and these work items can have multiple states
  example : 'Ready for build', 'Ready for deployment' etc</p>
  
  <p>2)  Based on the changes made to work item, is it possible to trigger a build ?</p>
  
  <p>For example if the workitem is moved to 'Ready for deployment' state, a deployment build should be triggered </p>
  
  <p>In other words how can we trigger builds based on changes to a work item ?</p>