fix encoding issue in word2vec example

[amygdala]

I added a note earlier but figured I should make it a proper issue.
Can you revisit this commit: 5393ac5#diff-300e5b2cbe160af1a9b56b074a6e6b04R144
which now works for py 3 but not py 2.7?
(whereas reverting the commit lets it work for py 2.7 but not py 3...)