add directory support for packaging

Hi,

When using Petrel to write python applications on top of storm, I find it's quite useful to support directory while packaging the code. Directories are helpful in organising those code and config files,  especially when I use thrift in application(those thrift-generated files could be a lot). So I add this directory support for packaging.

I don't know why the 'resources' directory in package is flatten previously.
Anyway I think maybe this change could be also helpful to someone who need it.