Untrack files
git update-index --assume-unchanged [filename]
Retrack file
git update-index --no-assume-unchanged [filename]
List untracked files
git ls-files -v|grep '^h'

Technical notes, and other ideas.
Untrack files
git update-index --assume-unchanged [filename]
Retrack file
git update-index --no-assume-unchanged [filename]
List untracked files
git ls-files -v|grep '^h'