Ensure Raintale GUI documentation contains details for setting it up on a production server

[shawnmjones]

The Raintale GUI production environment needs more robust infrastructure than provided by our Docker installation.

By default Wooey/Django uses SQLite as a database. SQLite allows for concurrent reads, but locks and queues concurrent writes. This is great for a single user, but not so good for a system that will satisfy multiple users. Django supports changing the backend database to something else.

Based on the Wooey documentation, it will use the default database for queuing, but RabbitMQ is "a more robust system" than the default database because RabbitMQ is specially designed for this queuing.

We should at least point to documentation that helps users set this up. We could also update our installer to alter the correct Django settings files as needed by administrators.

[shawnmjones]

This was completed as part of work for #30.