Add path package

For testing purposes we need to get the long path of filesystem paths
on Windows machines. By default non-UTF8 syscalls will return the short path
(Ex:"C:\PROGRA~1" instead of "C:\Program Files"). This package exports
previously private functions used in the symlink package to determine the
long path of a file/directory.
> Let's not expose the ugly version, only the nice string version. 

+1

Also, perhaps just "Long" might be a better name - it would then read "path.Long(xxx)"
which is has less redundancy.