Resolve "Rename hostname to domain"

In the bigbang values.yaml the first yaml key-pair is
hostname: bigbang.dev
This key is incorrectly named. This is a DOMAIN not a hostname. The key name should be
domain:

The yaml key hostname is deprecated but will still be supported indefinitely.
This code change allows the the BigBang Packages to switch to domain at any time without breaking anything.

Closes #730 (closed)