Use inotify events for logparser plugin

Closes #78
@ppp0 @kris-lab please review

The logic is highly influences by `tailf`'s [watch_file_inotify](https://github.com/karelzak/util-linux/blob/master/text-utils/tailf.c#L147).
Because when we *write* to a file (compared to *appending*), then we'll use the previous size of the fail as the point of where to start reading. E.g. we write new content and the file size changes from 100 to 50 characters, then we'll start at position 50 (which is the end of the file). We're also resetting the *current position* to the new size (50).