Perhaps this will fix the 3.4 build failure.
The problem is the old version of pip that ships with Python 3.4.0.  Maybe we can get Appveyor to use 3.4.1.
Apparently yaml is picky about whitespace.
Or maybe getting pip to upgrade itself will work.
pip's a bust on windows.  Try running green in-place instead.
Another try
And another.
Merge branch 'i32'.  Fixes #32.