upgrade to 4.5 and fix bug:self referencing loop

I upgrade Ext.Direct to 4.5 because my main project  is net 4.5 and use json.net 6 based net 4.5
and I use entity framework,It's always report error:self referencing loop,so I fixed it.
Now It's run well

我将Ext.Direct 的Target framework从.NET Framework 3.5 升级到 4.5，因为我的项目都是基于4.5的
我使用了Entity Framwork，调用的时候，总是会提示:self referencing loop，现在我解决了它，
现在整个世界都和谐了，呵呵