* Install pypy using chocolatey
* Enable coveralls test environment in AppVeyor
* Suggest maintaining build matrix in .travis.yml by using "tox --listenvs"
Fix#1254
- AppVeyor does not run matrix builds in parallel, so creating a matrix with the intent to
speed up the build will actually result in longer build times, as each matrix will execute
in a brand new VM.
- tox does not detect 64 bit installations in AppVeyor, it always installs interpreters
from C:\PythonX.Y, so there's no point to have 64bit builds
- No need for the auxiliary script "install.ps1" because all python versions we are interested
in are already pre-installed in AppVeyor