Combining application.json with whippet.json

[Stretch96]

Instead of having both config/application.json and whippet.json, would be good if they could be combined into whippet.json. Something along the lines of:

{
  "src": {
    "plugins": "https://github.com/wp-plugins",
    "wordpress": "https://github.com/WordPress/WordPress.git"
  },
  "plugins": [
  ],
  "wordpress": [
     "ref": "v4.5.3"
  ]
}