work around windows issue with ruamel.yaml

Author: mckaymatt

HISTORY.rst

@@ -2,7 +2,7 @@
 History
 =======
 
-0.8.2 (2017-06-23)
+0.8.3 (2017-06-24)
 ------------------
 
 * First release on PyPI.

appveyor.yml

@@ -77,7 +77,8 @@ install:
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
   - rustc -Vv
   - cargo -V
-  - "%PYTHON_DIR%\\python.exe -m pip install pip>=9.0.1 ruamel.yaml==0.14.12"
+  - "%PYTHON_DIR%\\python.exe -m pip install -U pip>=9.0.1 wheel"
+  - "%PYTHON_DIR%\\python.exe -m pip install ruamel.yaml==0.14.12 --no-binary :all:"
   - "%PYTHON_DIR%\\python.exe -m pip install -U urllib3[secure] scikit-ci==0.14.0"
   - "%PYTHON_DIR%\\python -m ci install"