Update ls-files so it now works with Git 2.16 and later

[westbury]

This fixes a problem that occurs when a Git repository is empty (the initial commit has not yet been made) and Git version 2.16 or later is being used.

With Git version 2.16, the ls-files command now requires '.' be specified to indicate all files. It is no longer acceptable to omit the arg. Without the fix, one got this:

With the fix one gets:

This will also fix the lsFiles for other users of the function.

[kittaakos]

I have verified it locally; it works as expected. 👍

Thank you for the help, @westbury!