title: Bind mvvm light Relaycommand to page loading event
body: <p>I am working on Window phone 8.1.
  I have a RelayCommand command which executes some method async. 
  I want to know how can I bind a page load event from a page to the RelayCommand in the view model?</p>
  
  <p>All the example I see are binding RelayCommand to a Button.</p>
  
  <p>How can I bind that to page load event? I see some example uses EventToCommand. But I am using Window phone 8.1, I dont' think I have the behaviour stuff some article I saw.</p>