title: Remote attribute doesn't trigger when field is blank
body: <p>I'm using <code>RemoteAttribute</code> for a particular field on my form. The purpose of it is not important. What is important is that it needs to fire the validation action whenever the field is changed. This is working fine for me except when the field is changed to be blank. </p>
  
  <p>I've Googled this but found no results. Does anybody know if <code>RemoteAttribute</code> does actually trigger for blank fields and if not, how it can be forced?</p>
  
  <p>Alternatively, can the remote validator be customised/modified to trigger for blank values?</p>