add uuid array support

I know I have sent a same pull request before at issue #50, but I can't find the changes in current master branch now.  

The sending changes has some minor improvements:
1) renamed ArranElementBuilder/ArrayElementBuilderFactory to ArrayAssistant/ArrayAsistantRegistry;
2) code refactoring for ArrayAsistantRegistry (ArrayElementBuilderFactory).

I think it looks better.  

Can you help review again and give your suggestions?  

Thanks,
Minglei Tu