zh_TW.po: fix typo

Simply 轉備 -> 準備

Signed-off-by: Ｖ字龍(Vdragon) <Vdragon.Taiwan@gmail.com>
zh_TW.po: improve translation

Signed-off-by: Ｖ字龍(Vdragon) <Vdragon.Taiwan@gmail.com>
zh_TW.po: update PO-Revision-Date

Signed-off-by: Ｖ字龍(Vdragon) <Vdragon.Taiwan@gmail.com>
po: update i18n files

$ python setup.py build_pot

Signed-off-by: David Aguilar <davvid@gmail.com>
core: Apply Python 3 change to code based around os.getcwdu

This is building on changes that @takluyver already made.  I changed out
instances of getcwdu with our Python version specific core.getcwd.  I
also added some very basic unit tests for those changes.