fixes #8484 - make SmartProxyAuth concern more useful to plugins

fixes #8049 - Add timezone to user

Refs #3809 - Remove useless assignments

Refs #969 - Foreman-side changes for serving templates from the proxy

Fixes #8005 - Convert allowed NIC types to strings

- allowed NIC type classes need to be registered now
- api for interfaces use lowercase human readable values for defining types
- fixed output of api's create action to the standard format

Fixes #7733 - Remove hosts.yml fixtures and use FactoryGirl instead

fixes #7372 - API v2 - accept PUT/POST requests with wrapped root node to add/remove has_many associations of child nodes

Fixes #5139 - leftovers subscribe_to_all_hostgroups

Remove user_xxx unnecessary tables and notices

Update subhostgroups removed

Fixes for migration of foreign keys

Remove users from compute_resource fixture

Remove table notices after fk are removed for pg/mysql

Refs #3809 - Use parentheses in method definitions

Refs #3809 - Fix a few rubocop TODOs