allow the external-scripts.json to be an object

specify scripts in a module to load:

{
  "module-name": [
    "scripts",
    "to",
    "load"
  ],
  "modulename-2": [
    "more",
    "scripts",
    "toload"
  ]
}

or the old array containing multiple module names loading all scripts in the
module:

[ "module-name", "modulename-2" ]