Add processes from package.json to Procfile

If in my package.json I define processes for the production environment, add them to a `Procfile`.

```js
{
  "name": "proc-pkg",
  "version": "0.0.0",
  "description": "Proof of concept for package.json process manifest",
  "main": "index.js",
  "author": "Jonathan Clem",
  "license": "MIT",
  "processes": {
    "production": {
      "web": "node web.js",
      "worker": "node worker.js"
    },
    "development": {
      "web": "node web.js",
      "worker": "node worker.js"
    }
  },
  "engines": {
    "node": "0.10.x"
  }
}
```