Merge pull request #96 from madig/fix-appveyor-pt4

Fix AppVeyor deploy, take four.

Author: madig

appveyor.yml

@@ -68,10 +68,11 @@ artifacts:
   - path: dist\*.whl
 
 on_success:
-  - >
-    IF "%APPVEYOR_REPO_TAG%" == "true"
-    (
-    python -m pip install twine
-    &&
-    python -m twine upload dist/*.whl
-    )
+  - ps: >-
+      if ($env:APPVEYOR_REPO_TAG -eq 'true') {
+        Write-Output ("Deploying " + $env:APPVEYOR_REPO_TAG_NAME + " to PyPI...")
+        pip install --upgrade twine
+        twine upload (ls dist\*.whl)
+      } else {
+        Write-Output "Not deploying as this is not a tagged commit"
+      }