title: Kendo Upload: sync two conrols upload complete
body: <p>I have on html page  two kendo upload widgets without autoupload.
  When I press button, both controls starts uploading files to the backend.
  When all controls sucessfully uploaded files, I need to perform some post processing.</p>
  
  <p>I can subscribe to the complete event, but how do I catch the moment, when both controls are completed?</p>