[pytest-dev] removed outdated japanese docs

[holger krekel]

Hi all,

i just removed the japanese documentation because it's just a
translation of the english docs a the time of the pytest-2.2 release.
So it's more misleading now than helpful.  Also i am not convinced a
test tool used by software developers should care much for non-english TBH.
If you disagree and/or would like to maintain the japanese docs, please tell! 

There still remain available at http://pytest.org/latest-ja for the time
being.

best,
holger