appveyor: print version of python to be used

Author: sriram-mv

.appveyor.yml

@@ -19,6 +19,7 @@ install:
 - "set PATH=%PYTHON%\\Scripts;%PYTHON%\\bin;%PATH%"
 - "%PYTHON%\\python.exe -m pip install -r requirements/dev.txt"
 - "%PYTHON%\\python.exe -m pip install -e ."
+- "python --version"
 - "set PATH=C:\\Ruby25-x64\\bin;%PATH%"
 - "gem install bundler --no-ri --no-rdoc"
 - "bundler --version"