add appveyor build

.npmignore

@@ -1,2 +1,2 @@
-node_modules
-.idea
+node_modules/
+.idea/

README.md

@@ -1,7 +1,8 @@
 ## gulp-lazyimagecss
 
-[![Build Status](https://travis-ci.org/weixin/node-lwip.svg)](https://travis-ci.org/weixin/gulp-lazyimagecss "Build Status")
 [![NPM Version](http://img.shields.io/npm/v/gulp-lazyimagecss.svg?style=flat)](https://www.npmjs.com/package/gulp-lazyimagecss "Package version") 
+[![Build Status](https://travis-ci.org/weixin/node-lwip.svg)](https://travis-ci.org/weixin/gulp-lazyimagecss "Build Status")
+[![Windows Build status](https://img.shields.io/appveyor/ci/weixin/gulp-lazyimagecss/master.svg?label=Windows%20build)](https://ci.appveyor.com/project/weixin/gulp-lazyimagecss/branch/master) 
 [![NPM Downloads](https://img.shields.io/npm/dm/gulp-lazyimagecss.svg?style=flat)](https://www.npmjs.com/package/gulp-lazyimagecss "NPM Downloads") 
 
 [![Join the chat at https://gitter.im/weixin/gulp-lazyimagecss](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/weixin/gulp-lazyimagecss?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)

appveyor.yml

@@ -0,0 +1,36 @@
+# AppVeyor file
+# http://www.appveyor.com/docs/lang/nodejs-iojs
+# http://www.appveyor.com/docs/appveyor-yml
+
+version: "{build}"
+
+clone_depth: 10
+
+environment:
+  matrix:
+    - nodejs_version: 0.12
+    - nodejs_version: 4
+
+# Install scripts. (runs after repo cloning)
+install:
+  # Get the latest stable version of Node.js or io.js
+  - ps: Install-Product node $env:nodejs_version
+  # install modules
+  - npm install
+
+# Post-install test scripts.
+test_script:
+  # Output useful info for debugging.
+  - node --version && npm --version
+  # run tests
+  - npm test
+
+# Don't actually build.
+build: off
+
+matrix:
+  fast_finish: true
+
+cache:
+  - C:\Users\appveyor\AppData\Roaming\npm-cache -> package.json         # npm cache
+  - node_modules -> package.json                                        # local npm modules