SuspendEvents also suspends recompositing on... 

CompositeDynamicObjectCollection

Issue: https://github.com/AnalyticalGraphicsInc/cesium/issues/1452

Summary of changes:  Two new properties added to the object, `_shouldRecomposite` and `_suspendCount`.  `_suspendCount` acts exactly like `DynamicObjectCollection`'s `suspendCount` and the `_shouldRecomposite` is present as a performance enhancement, to prevent a `recomposite()` call if it is not required.  

The `recomposite` function has only changed in line 145-146 in that we set `_shouldRecomposite` to true and wrap the whole function in an `if` check, screwing with the formatting.