Should we allow the creation of empty directories?

[wolfv]

The paths.json allows for a directory path type. This is only useful for creating empty directories.

Sometimes it might be desirable for a package to create an empty directory, for example, to have a known place to store configuration data in etc.

However, conda-build filters all directories (including empty ones) unconditionally and thus never writes the path_type: directory (at least to my knowledge, and I made a quick test that confirmed this).

I think we should allow the creation of empty directories.

[wolfv]

Apparently there is a workaround people use with conda-build which is to create a folder and add a .empty file in the folder (to make sure it stays around).