Renaming katello-agent to katello-host-tools

As part of this PR: a discussion came
up of renaming the base package to 'katello-host-tools', while moving
all of the gofer-specific bits into katello-agent.

The benefit of this is that a user can install katello-agent and get all
the tools including the gofer bits, or can install katello-host-tools
and just get utilities and commands to support errata/package
applicability and tracer reporting.

This naturally leads to renaming of the git repo from katello-agent to

Please speak up if you have questions or concerns!