Revert "completion: Install via setup.py"
Revert "completion: Install via setup.py"

This reverts commit 51e6c6cf0d5f8f51b23932dcad060ba7ac0d1b46.

There are two problems with this commit:

1. /etc/bash_completion.d is not standard across all systems.
2. There appears to be issues with installing data_files in wheels.

Just drop this. We'll add some documentation and let the user handle
installing this themselves.

JonathonReinhart/scuba,JonathonReinhart/scuba,JonathonReinhart/scuba