add appveyor.yml for windows CI

Author: AtsushiSakai

appveyor.yml

@@ -0,0 +1,12 @@
+init:
+- ECHO %PYTHON%
+
+environment:
+  matrix:
+  - PYTHON: C:/Python36-x64
+
+install:
+  - ps: (new-object net.webclient).DownloadFile('https://raw.github.com/pypa/pip/master/contrib/get-pip.py', 'C:/get-pip.py')
+  - "%PYTHON%/python.exe C:/get-pip.py"
+  - "%PYTHON%/Scripts/pip.exe install pillow==2.9.0"
+