Fix Bug in case xml children have namespace but not have data

Hi,
I found an another issue when you try to serialize and deserialize an XML that 
don't have namespace in root, and one of children have a namespace but don't have a value.
in example if you have an XML like this
![image](https://f.cloud.github.com/assets/4958307/2240834/9e72661a-9cb0-11e3-8076-52bc85548cfd.png)

it will be deserialized to that thing:
![image](https://f.cloud.github.com/assets/4958307/2240836/bfd45c28-9cb0-11e3-9e0c-b6897662b5e4.png)

I fix this issue by chnaging the line that remove namespace after push scope, in XMLNodeConverter.

I write a test that fail, and after fix pass.
All other test pass too.
Thanks to accepts this request.

Ygal