This modernizes the way we request input and display output on

prepare-dev.py, utilizing more of rb-site's ConsoleUI. This is a

better, more consistent way of displaying information and prompting for

information.
The text has been updated to be more user-friendly, to offer

guidance for when things go wrong, and to provide next steps when the

environment is prepared.

Ran through prepare-dev.py with a brand-new clone and database, and also

with an existing one.
Verified dependencies were installed.
Verified each new text string was correct and free from typos.