Allow for paths to be excluded from scanning.

[egibs]

When scanning a directory, we should be able to exclude arbitrary paths via something like --exclude-paths.

A good example here is when scanning samples/macOS which has the bincapz binary in it. Since we tend to scan bincapz on its own, we could do --exclude-paths=macOS/clean/bincapz to allow all of the other files to be scanned.