AnalyticalGraphicsInc/cesium — pull request #570 by cmorse (2013-03-18 22:33:29+00:00)
Title: Deleting czml Objects

I put together some changes to allow for czml Object to be deleted from both a CompositeDynamicObjectCollection and a DynamicObjectCollection.

To delete, the czml packet just needs to look like this:
```javascript
{
"id": "GroundControlStation",
"delete": true
}
```