Fixes #8424 - Controller concerns are loaded twice

config/application.rb, we are adding the controller concerns twice
folder to autoload_paths
Fixes #4613 - Remove duplicate scoped search from taxonomies
Fixes #8425 - n+1 query on audits index

Audits index include users who performed actions, and these are being
called with n+1 queries. Fix should be as simple as providing the
users through the controller with an includes.
Refs #3809 - Remove useless assignments
Fixes #8405 - Filter :interfaces_attributes when calculating templates_used
Fixes #7908 - normalize mac before host get saved

For some reason we save host without running valdiations when we import
attributes from facts. Therefore we have to take care of mac
normalization by ourselves. We have to normalize it just after setting
new value because save can occure anytime.
Fixes #8428 - Connecting audits to existing users