title: Breeze - define key to add entity
body: <p>I want to add an Entity to my Manager.
  The manager is saved in my MasterViewmodel, and I'm working with knockout.</p>
  
  <pre><code>Error: Cannot attach an object to an EntityManager without first setting its key or setting its entityType 'AutoGeneratedKeyType' property to something other than 'None'
  </code></pre>
  
  <p>My code:</p>
  
  <pre><code>var item = {           
          GuidUser: masterViewModel.UserID,
          GuidProject: ProjectID,
          Start: startTime,
          End: stopTime,
          Description: workDone,
          IdCustomer: null,
          timestampId: null,
          Charged: false,
          ToCharge: toCharge,
          };
  var item2 = masterViewModel.breezeProjectManager().createEntity('Timestamp', item);
  masterViewModel.breezeProjectManager().addEntity(item2);
  </code></pre>
  
  <p>But how to set a Key? </p>