Revert "Attempt to fix security issue with withCwd and '../' in paths."

This reverts commit 57a9e5f9e0c9fd3e5fbdd7f847d5f0116dbd5a4a.

See https://github.com/sstur/nodeftpd/commit/57a9e5f9e0c9fd3e5fbdd7f847d5f0116dbd5a4a#commitcomment-5232986
Revert "Extend tests for withCwd (handle Windows value for path.sep)"

This reverts commit 102cd54de5c6af4c94468e1933369acc26f1879f.

https://github.com/sstur/nodeftpd/commit/57a9e5f9e0c9fd3e5fbdd7f847d5f0116dbd5a4a#commitcomment-5232986
Revert "Add tests for withCwd function"

This reverts commit 53e2d13fa15b696dbee15b215620f57f7f0be9e0.

https://github.com/sstur/nodeftpd/commit/57a9e5f9e0c9fd3e5fbdd7f847d5f0116dbd5a4a#commitcomment-5232986