Add support for C++11 range-based for-loop

for(auto &o : my_json_value->u.object)
{
std::cout << o.name << std::endl;
}
And similar for arrays. No type checking, unfortunately - I couldn't
manage that.

Fix indentation
Merge pull request #1 from udp/master

Merge upstream changes
Merge pull request #21 from LB--/master

Add support for C++11 range-based for-loop