add heroku postbuild

Author: Peterr181

package.json

@@ -8,8 +8,7 @@
     "start": "node ./server/server.js",
     "dev": "nodemon ./server/server.js",
     "test": "echo \"No tests specified\"",
-    "postbuild": "npm run build-client",
-    "build-client": "cd client && npm install && npm run build && mv ./dist ../server/public"
+    "heroku-postbuild": "cd client && npm install && npm run build && mv ./dist ../server/public"
   },
   "keywords": [],
   "author": "",