Fix copying of binary files in nested paths

This solves a problem where files in nested, templated paths would raise an IOError:
e.g. {{cookiecutter.repo_name}}/{{cookiecutter.repo_name}}/binaryfile

This also removes the requirements file from tox.ini (since it doesn't exist). Instead, deps are
specified explicitly.
Force-commit the nested .DS_Store file to fix tests.
Update the outer .DS_Store so git doesn't complain.