Fix endless loop on windows with Finup.sync

[mgreter]

Not sure if this is the correct fix, but I guess Path.join and Path.resolve should behave pretty much the same, but the later will return a normalized absolute paths and make sure excessive .. references are removed. It might be enough to use Path.normalize(Path.join(...)) inside the loop, but the documentation for these functions is a bit incomplete for my taste. They i.e. do not carify if symbolic links will be resolved or not (I guess it's just a logical path cleanup from cwd). So this should work AFAICS.