fix onFile: removed cb call that have not sense

In function `onFile` if `!modified` callback called. `modified` is not declared in `README.md`.
If we have a lot files (100, for example) because of this call `running` and `finished` has wrong values so:
1. Callback could not be called (this could be never true ` if ((started === finished) && (running === 0)`)
2. Callback could be called earlier then it should.

`modified` flag should be added to `README.md` I think or be deleted, because nobody knows about it.