fixes #4599 - DNS and DHCP records for BMC and managed interfaces not using FQDN

(cherry picked from commit 21e07e92ca2d0341a09de48fadfa95625f6d9f55)

Fixes #4851: a SmartProxy.with_features scope replaces feature-specific scopes generated during class loading

fixes #4123 - libvirt imaging support using backing volumes

fixes #3697, #3701 - more comprehensive field validations

Fixes #3481 - Don't have to set a hostname for each interface, but it must be unique if it is set.

fixes #2741 - rails 3 syntax

fixes #2411 - move STI models in /models and /lib/foreman/models to sub-folders

fixes #2713 - do not update nics table on every host update as a workaround to bug #2489

fixes #2489 - fixes BMC password caused by rails bug accepts_nested_attributes_for and serialized child field

fixes #2325 No A record created in domain when provisioning image based vm