Add buildout

Buildout is used all Plone projects, and probably all Zope projects.

Buildout is an automation tool written in and extended with Python and designed to solve 2 problems:
1. Application-centric assembly and deployment
2. Repeatable assembly of programs from Python software distributions

Docs: www.buildout.org/
PYPI: https://pypi.org/project/zc.buildout/
Depends on: setuptools

該 issue 指出了 Buildout、其位於 www.buildout.org 的文件、其 PyPI 頁面以及作為相依項的 setuptools，但沒有指定任何儲存庫檔案或測試。首先定位專案中如何表示套件管理工具，然後利用這些參考資訊新增 Buildout 及其描述和相依資訊。當 Buildout 一致地出現在互動式工具表中時，即表示完成。

由索引模型根據 Issue 內容生成。