Assist users who need to identify dirt in protected commits

Write CSV files listing all protected dirt to disk- helping users
who have situations where it's not trivial to see where their bad stuff
is.

http://stackoverflow.com/questions/18647400/git-filter-branch-to-remove-strings-but-where-strings-contain-and-other-c/18651069#comment27746976_18651069

These files pretty much fix #14, as they contain line number information
that indicates where the dirty content is (they don't contain the
dirty content, as it might be a password the user would rather we
did not write out)


https://github.com/rtyley/bfg-repo-cleaner/issues/14