Resource.unpack: install invisible files and dirs

Since patches sometimes change .gitignore and .travis.yml, it's
desirable to install them along with everything else if a resource needs
patching. Also, for resources that are git respositories, this allows
install to interact with git objects other than the commit specifically
checked out. More generally, this may help to avoid subtle issues by
preserving the fidelity of resources in cases where invisible dot files
play a functional role.

Closes #329.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>