Child version test

As discussed here:
https://groups.google.com/forum/?fromgroups=#!topic/symfony-cmf-devs/--3J2hbMsa8

I've created **failing** test cases to show how I expect versioning to work with a node type child definition "on version copy".

In effect I'm expecting versions to be 'in sync' with this method, so that when creating a version of the parent, a new version of the child is also created; When reverting the parent, any changes to the child are also reverted.

I could be wrong of course, and I'm not 100% sure my node type is correct...

Also, there's probably a better place to load the node type definition, but I don't think it's ready to go in the standard fixtures.