rename logic is incorrect on Linux

[lucagrulla]

the rename logic didn't work without swapping:

if (filename === undefined || filename !== this.filename) {

to

if (filename === undefined || filename === this.filename) {

this was on Linux,[...] It would seem on Linux that the rename argument is the "from" filename, I guess?[...]

Originally posted by @bruce-one in #130 (comment)

[joac]

Had this issue, I think the approach from https://github.com/logdna/tail-file-node to handle renames is a lot more reliable.