Remove prod script

e3ce1fb removed build/prod-server.js so it `npm run prod` does not work anymore.

Author: bernhardreiter

package.json

@@ -7,7 +7,6 @@
   "license": "MIT",
   "scripts": {
     "dev": "node build/dev-server.js",
-    "prod": "node build/prod-server.js",
     "build": "node build/build.js",
     "unit": "karma start test/unit/karma.conf.js --single-run",
     "e2e": "node test/e2e/runner.js",