Fixes #11924 - Substitute .scoped by .where(nil) to force return relation

On Rails 4 .scoped is deprecated. Calling .all on the model returns the
equivalent ActiveRecord relation object on Rails 4, but on Rails 3 it
returns an Array right away.

A proper replacement we can use is where(nil) - it's ugly but it returns...

fixes #12207 - objects with ancestors should not call ancestors if cached

up until now, ancestry objects always called their ancestors when
linking to the object because to_param called get_title instead of title
(which can be cached)
this caused a LOT of pointless queries, slowed down Hosts#index alot

Fixes #11987 - Check exit code of deployment scripts

This commit fixes checking exit codes returned from provisioning templates, which were ignored
because of sending results through pipe to command tee. Also adds optional host deleting if deployment
fails because of non zero exit code. This can be configured by setting clean_up_failed_deployment...

Fixes #10988 - Remove 1.11 deprecations

Fixes #12067 - Delegated methods need to be public, not protected

generate_pxe_template and require_ip_validation? are delegated to
primary interface on Host::Managed. However, these methods are
protected. On Rails 4, protected methods cannot be called through a...

fixes #11375, #11782 - validate a host's lookup_values

Enabling validation ensures the casting and validation within
LookupValue runs during host/hostgroup save. Tweaks to hostgroup
cloning ensure that the newly cloned hostgroup now passes validation
when it has associated lookup values....

fixes #11945 - fix undefined variable in param_true/false helpers

fixes #11883 - fix classes accessors when cloning host groups

Ensures parameters from classes via config group associations show up
under the parameters tab when cloning host groups.

Fixes #11850 - improved DNS error message

Fixes #11814 - model_name needs to be stringified on Rails 4