stringify: add new method

[sergkudinov]

No description provided.

[wdavidw]

Please strip down your example to the essential, why defining host and port if you don't use it.

[sergkudinov]

If you talk about ../doc/api/stringify.md, then I use host and port options below in the examples.
for example:

app.compile([{
  config: "app.yml"
},{
  command: "start",
  host: "127.0.0.1",
  port: 80
}]).should.eql(
  ["--config", "app.yml", "start", "--host", "127.0.0.1", "--port", "80"]
);