YottaDB/DB/YDBDoc#355 requests the creation of an Applications Manual demonstrating how to use YottaDB to build applications in a variety of domains. One of these domains is web application development.

To satisfy the request for a web application using YottaDB, this commit implements a simple recipe application named YDBApron using the YDBPython for database operations and the Flask web development framework for application logic.

Since YDBApron is a fully functional, self-contained application, there are no discrete changes to log in this commit.

So, instead of going through line-by-line changes, this commit message simply provides an overview of the application itself as well as its data model.

YDBApron is a simple [Model-View-Controller (MVC)](https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller) application that uses a conventional Flask application structure:

```
    ├── COPYING
    ├─...