test: use normalize() for unicode paths

OS X 10.11 changed the unicode normalization form of certain code points
returned by system calls like getcwd() from NFC to NFD which made
results in this test failing.

The consensus of https://github.com/nodejs/node/issues/2165 is to delegate
the task of unicode normalization to the user, and work will continue to
document how to handle unicode in a form-sensitive file system.

PR-URL: https://github.com/nodejs/node/pull/3007
Fixes: https://github.com/nodejs/node/issues/2165


Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>