Making xunit work with latest nose

Making xunit work with latest nose...
Here is code line from nose where _forceUnicode is changed:
https://github.com/nose-devs/nose/commit/b3198e0c8586030d3366d5c5ea762d6b4e4b2e29#diff-968d09c42e9e5cbcf42f39bd99e2aa7eL219