Add pypy as an allowed failure
more detailed error messages from Image.py
Possible fix for pypy

Idea from http://www.tismer.com/pypy/irc-logs/pypy/pypy.2013-11-18.log.html
Possible fix for pypy

Idea from https://github.com/cpbotha/nvpy/issues/19#issuecomment-9732016
Forgot sudo
Merge pull request #571 from hugovk/master

Add PyPy to the Travis build
Merge pull request #566 from larsmans/error-messages

more detailed error messages from Image.py
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