[AppVeyor] `python` should use python 2

appveyor.yml

@@ -46,7 +46,7 @@ install:
     - neko -version
     # setup python
     - cmd: mklink C:\Python34-x64\python3.exe C:\Python34-x64\python.exe
-    - set PATH=C:\Python34-x64;%PATH%
+    - set PATH=%PATH%;C:\Python34-x64
 
 build_script:
     - 'cd %APPVEYOR_BUILD_FOLDER%'