Add appveyor deploy script

appveyor_deploy.yml

@@ -0,0 +1,17 @@
+clone_depth: 1
+version: '{build}'
+skip_non_tags: true
+image: Visual Studio 2017
+configuration: Release
+platform: Any CPU
+before_build:
+- ps: if($env:appveyor_repo_tag -eq 'True') { Update-AppveyorBuild -Version $env:appveyor_repo_tag_name }
+build_script:
+  - cmd: dotnet pack osu.Game.Resources /p:Version=%APPVEYOR_BUILD_VERSION%
+artifacts:
+  - path: osu.Game.Resources/bin/Any CPU/Release/**/*.nupkg
+deploy:
+  - provider: Environment
+    name: nuget
+  - provider: Environment
+    name: github