Add an appveyor config

Author: pimterry

appveyor.yml

@@ -0,0 +1,29 @@
+platform:
+- x64
+
+environment:
+  nodejs_version: "10"
+
+cache:
+- '%APPDATA%\npm-cache'
+- '%USERPROFILE%\.electron'
+- node_modules
+
+branches:
+  only:
+  - master
+  - /^v\d\.\d\.\d/
+
+install:
+- ps: Install-Product node $env:nodejs_version $env:platform
+- set PATH=%APPDATA%\npm;%PATH%
+- npm install
+- npm update
+
+build_script:
+- node --version
+- npm --version
+- if %APPVEYOR_REPO_TAG% EQU false npm run make
+
+deploy_script:
+- IF %APPVEYOR_REPO_TAG% EQU true npm run publish