Use prompt instead of argv arguments in scripts

This makes it easier to handle truffle arguments which we for example
need to specify the network.
So we ask the user for input instead on using the argv array which might
change.

package.json

@@ -25,6 +25,7 @@
   "homepage": "https://github.com/67P/truffle-kredits#readme",
   "devDependencies": {
     "ganache-cli": "^6.0.3",
+    "promptly": "^3.0.3",
     "truffle": "^4.1.3",
     "zeppelin-solidity": "^1.7.0"
   },