Add folder support.

[ghost]

Hi,
Could you add support for folders ex:
concat -o output.css ./folder
It would make the package.json CLI scripts lines cleaner / easier to maintain.

[maikthomas]

@coldtelling I seem to have achieved this with concat -o output.css folder/*

[ghost]

@maikthomas thanks !

[smohadjer]

But this doesn't work with subfolders, that is only files directly inside the folder get concatenated, not those in subfolders.