serve: Split the server code in a couple modules inside a `serving` package. This makes the `serve` command's code a bit more removed from implementation details, and paves the way for the CMS mode.

{
  "name": "PieCrust",
  "version": "0.0.1",
  "private": "true",
  "dependencies": {
    "bootstrap": "~3.3.2"
  }
}