Added Appveyor config file.

.appveyor.yml

@@ -0,0 +1,16 @@
+version: 1.0.{build}
+os: Visual Studio 2015
+platform:
+  - x86
+branches:
+  only:
+    - master
+install:
+ - ps: (new-object net.webclient).DownloadFile('https://www.python.org/ftp/python/3.4.4/python-3.4.4.msi', 'python-3.4.4.msi')
+ - ps: msiexec /i python-3.4.4.msi /quiet /qn /norestart
+ - cmd: copy c:\python34\python.exe c:\python34\python3.exe
+ - ps: (new-object net.webclient).DownloadFile('https://dl.dropboxusercontent.com/u/37517477/ninja.exe', 'ninja.exe')
+build_script:
+  - cmd: echo No build step.
+test_script:
+  - cmd: c:\python34\python3 run_tests.py --backend=ninja