add appveyor badge

mpictor · mpictor · commit 1a757024c450 · 2015-08-10T21:04:10.000-04:00
diff --git a/README.md b/README.md
@@ -1,5 +1,5 @@
 Travis-CI build status:
-[![Build Status](https://travis-ci.org/stepcode/stepcode.svg?branch=master)](https://travis-ci.org/stepcode/stepcode)
+[![Build Status](https://travis-ci.org/stepcode/stepcode.svg?branch=master)](https://travis-ci.org/stepcode/stepcode) [![Build status](https://ci.appveyor.com/api/projects/status/3fbr9t9gfa812oqu?svg=true)](https://ci.appveyor.com/project/mpictor/stepcode)
 
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 STEPcode v0.8 -- stepcode.org, github.com/stepcode/stepcode
