Fixes #4121: Removes unused configuration values.

Since turning Katello into a Foreman plugin, some configuration values
have become unused. These unused configuration options have resulted
from either no longer being the server, functionality moving into
Foreman or the removal of headpin fencing.
Merge pull request #4641 from ehelms/fixes-4121

Fixes #4121: Removes unused configuration values.
fixes #7705 - adding errata counts to content host details

This brings errata, repository association to errata, and applicable errata for systems into
the database. Also remove the Errata class that was based on Elasticsearch
Merge pull request #4705 from jlsherrill/db_errata

fixes #7705 - adding errata counts to content host details
refs #7156 - rubocop fixes for katello/helpers
Refs #7156: Fix config/ Rubocop offenses.
refs #7156 - updating models for new rubocop style
Refs #7156: Removing unneeded files Rubocop was checking.
Refs #7156: fix rubocop offenses in app/controllers.
refs #7156 - updating rubocop style for migrations
refs #7156 - rubocop - adding to app/views/*.rabl files
Refs #7156: Fix lib/ Rubocop offenses.
Merge pull request #4726 from waldenraines/rubocop-controllers

Refs #7156: fix rubocop offenses in app/controllers.
Merge pull request #4724 from ehelms/refs-7156-config

Refs #7156: Fix config/ Rubocop offenses.
Merge pull request #4725 from ehelms/refs-7156-cleanup

Refs #7156: Removing unneeded files Rubocop was checking.
Merge pull request #4722 from bbuckingham/issue-7156

refs #7156 - rubocop fixes for katello/helpers
refs #7156 - test updates for model changes
Merge pull request #4728 from komidore64/rubocop-views-dir

refs #7156 - rubocop - adding to app/views/*.rabl files
Merge pull request #4723 from ehelms/refs-7156-lib

Refs #7156: Fix lib/ Rubocop offenses.
Refs #7156 - Disable some cops