Configure Appveyor CI (attempt #6)

Author: avh4

package.json

@@ -7,7 +7,7 @@
     "url": "git://github.com/avh4/elm-upgrade.git"
   },
   "scripts": {
-    "test": "prettier -l upgrade.js src/**/*.js && ./tests/make_links.sh && cram -v ./tests"
+    "test": "prettier -l upgrade.js src/**/*.js && sh ./tests/make_links.sh && cram -v ./tests"
   },
   "author": "Aaron VonderHaar <[email protected]>",
   "license": "MIT",