Add appveyor for automatic tests (#7)

* add appveyor.yml

* add appveyor-badge

Author: chrishelgert

.appveyor.yml

@@ -0,0 +1,20 @@
+environment:
+  matrix:
+    - nodejs_version: "6"
+    - nodejs_version: "7"
+
+install:
+  - ps: Install-Product node $env:nodejs_version
+  - yarn install
+
+test_script:
+  - node --version
+  - npm --version
+  - npm test
+
+cache:
+ - node_modules
+ - "%LOCALAPPDATA%/Yarn"
+
+# Don't actually build.
+build: off

README.md

@@ -2,6 +2,7 @@
 
 [![npm version](https://badge.fury.io/js/react-handler.svg)](https://badge.fury.io/js/react-handler)
 [![Build Status](https://travis-ci.org/chrishelgert/react-handler.svg?branch=master)](https://travis-ci.org/chrishelgert/react-handler)
+[![Build status](https://ci.appveyor.com/api/projects/status/c5qo9wa0n4uwakfj?svg=true)](https://ci.appveyor.com/project/chrishelgert/react-handler)
 [![codecov](https://codecov.io/gh/chrishelgert/react-handler/branch/master/graph/badge.svg)](https://codecov.io/gh/chrishelgert/react-handler)
 
 > A react-component for handling typical react/redux-states (loading, error, ...)