Update appveyor.yml

appveyor.yml

@@ -22,6 +22,6 @@ notifications:
   on_build_success: true
   on_build_failure: true
   on_build_status_changed: true
-cache:
-- packages -> src\**\packages.config, tests\**\packages.config
-- tools -> build.cake, tools\packages.config
+artifacts:
+  - path: artifacts\test-results\*.xml
+  - path: artifacts\nuget\*.nupkg