fix generating a list of files/directories ignored by git

"git ls-files --others --ignore --exclude-standard --directory" doesn't include
the files that for example get ignored by this .gitignore line:
-----
default/*
-----

"git ls-files --others --ignored --exclude-standard" includes these files, but
doesn't include this:
-----
folder/
-----

So combine those 2 commands.

Reference: http://stackoverflow.com/questions/466764/show-ignored-files-in-git#answer-1446609