Replace treeify with object-treeify

[Lukas Siemon]

I've just spend some time fighting with treeify and then decided to write my own version that is much more concise and efficient.

I'm just curious if you would be interested in replacing treeify with object-treeify. Functionality wise they should be identical and I'd be very happy to create a pull request.

I'm just trying to promote my npm packages a bit more, however I believe that this is an upgrade to code quality and efficiency.

Edit: If you're looking for a good reason to change - object-treeify sorts the output alphabetically, not reverse as treeify seems to do.