[appveyor] Add latest python version

Author: mpsonntag

appveyor.yml

@@ -4,10 +4,14 @@ environment:
       PYVER: "2.7"
     - PYTHON: "C:\\Python35"
       PYVER: "3.5"
+    - PYTHON: "C:\\Python36"
+      PYVER: "3.6"
     - PYTHON: "C:\\Python27-x64"
       PYVER: "2.7"
     - PYTHON: "C:\\Python35-x64"
       PYVER: "3.5"
+    - PYTHON: "C:\\Python36-x64"
+      PYVER: "3.6"
 
 build: false