Adding appveyor to signpath

appveyor.yml

@@ -0,0 +1,27 @@
+version: 5.0.{build}
+branches:
+  only:
+  - master
+  - v4
+image: Visual Studio 2017
+configuration: 
+  - Debug
+  - Release
+before_build:
+  - cmd: nuget restore LiteDB.sln
+build:
+  project: LiteDB.sln
+  publish_nuget: true
+  verbosity: minimal
+for:
+-
+  matrix:
+    only:
+      - configuration: Release
+  artifacts:
+    - path: LiteDB\bin\Release\LiteDB*.nupkg
+  deploy:
+  - provider: Webhook
+    url: https://app.signpath.io/API/v1/f5b329b8-705f-4d6c-928a-19465b83716b/Integrations/AppVeyor?ProjectKey=LiteDB.git&SigningPolicyKey=release-signing
+    authorization:
+      secure: 3eLjGkpQC1wg1s5GIEqs7yk/V8OZNnpKmpwdsaloGExc5jMspM4nA7u/UlG5ugraEyXRC05ZxLU4FIfH2V2BEg==