running 'py' as tox environment is a shorthand for 'basepython=python', which means
tox will create the venv using the 'python' executable which is first in the path,
which in the case of Appveyor environment, it's the same where tox was installed in.
We no longer run tests on python3.4 on Windows; 2.7 and 3.5 are enough for Windows I believe.
We do test python3.4 on Linux (not for long, I hope).
We shall add 3.6 when Appveyor provides that by default.
Update appveyor.yml to follow the most recent recommendation from PyPA Packaging User Guide:
http://python-packaging-user-guide.readthedocs.org/en/latest/appveyor/
- set DISTUTILS_USE_SDK=1 only for Python34-x64. It seems like we no longer need to do that for Python2.7-x64;
For more info check this: https://github.com/ogrisel/python-appveyor-demo/issues/39
- run tox using 'with-compiler.cmd' batch script so that Brotli extension can be built from git source with the correct MSVC and Windows SDK versions (btw, I wish brotli was on PyPI already so we could just `pip install brotli` and done!);
- define TOXPYTHON variable to make sure tox uses the correct python interpreter. Previously, in fact, the 'py34' toxenv was always picking up the 32-bit interpreter, even when we were testing the 64-bit Python 3.4 :(...
- add PowerShell command to enable 'rollout builds' feature, as done on 'python-appveyor-demo':
f54ec3593b/appveyor.yml (L81-L89)
- call pip via `python -m pip` to make sure we are running the just updated pip version, instead of Appveyor's pre-installed pip
- Remove unused stuff
It seems like Appveyor no longer needs the batch script to configure the MSVC compiler variables.
Also, since appveyor already comes with all the python versions we need, we don't need the install.ps1 script any more.
Brotli is now installed by tox from requirements.txt inside the test virtualenv.
