Add appveyor.yml file.

Author: Azganoth

.gitignore

@@ -1,4 +1,3 @@
 node_modules
-prebuilds
 build
 *.log

appveyor.yml

@@ -0,0 +1,26 @@
+image: Visual Studio 2015
+
+environment:
+  NODEJS_VERSION: "8"
+
+platform:
+  - x64
+  - x86
+
+install:
+  - ps: Install-Product node $env:NODEJS_VERSION $env:Platform
+  - node --version
+  - yarn --version
+  - yarn install
+
+test_script:
+  - yarn run test
+
+build: off
+
+branches:
+  only:
+    - master
+
+deploy_script:
+  - IF "%APPVEYOR_REPO_TAG%" == "true" (yarn run prebuild && yarn run prebuild:upload -u %PREBUILD_UPLOAD%)