Allow moving of files to subfolders

[dufferzafar]

We'll be able to do things like:

"./path1_subpath1_name.jpg" => "./path1/subpath1/name.jpg"

Fixes #18.

[laurent22]

Hi, thanks for the pull request, however I cannot get it to work. I've created three files:

$ touch 123 456 789

Then I've ran massren and renamed this:

123
456
789

to this:

1/23
4/56
7/89

But the files have simply been renamed to "23", "56" and "89" and no sub-directory has been created. Am I using it wrong, or is something not working?

[dufferzafar]

I hate saying this but... "It's working fine on my machine." :?

You're running the code from my mkdir branch, right?

[laurent22]

Right, I had the right branch but was using the wrong executable. Looks like the feature is good to merge then, thanks a lot.