title: projection query for ndb.Expando (1.7.6)
body: <p>the following query returns keys only even I want to return the attribute Name which is a ndb.StringProperty of a ndb.Expando entity.</p>
  
  <p><code>cls.query().order(cls.Name).fetch(100, projection=[cls.Name])</code> #.. WHAT?</p>
  
  <p>If I do something like <code>cls.query().order(cls.Name).fetch(100)</code> works</p>
  
  <p>Question, can I use projection over ndb.Expando? I've even tried 
  <code>cls.query().order(cls.Name).fetch(100, projection=[ndb.GenericProperty('Name')])</code> and get only keys plus null values for the other properties in the result.</p>
  
  <p>I'm on 1.7.6. Help is appreciated.</p>