fixes #3889 - don't reload nested lookup keys during render, so validation errors aren't lost

Merge branch 'fixes-3872' of git://github.com/ehelms/foreman into ehelms-fixes-3872

Fixes 3872: Provides a better customizable application layout that
conforms to HTML5 best practices.

This change aims to provide a more customizable application layout by first
splitting the base layout, menu and content out into their own view files.
The base layout provides generic hooks and only the most basic common data...

fixes #2374 - added allocation option to libvirt VM

fixes #3339 - nested fact support, allow fact importers to be registered by plugins

Fixes #3721 - Map OS family to a display variant

Fixes #3720 - Add description field to operatingsystem

fixes #3790 - Added support for isolated engine to foreman menu

fixes #3491 - API v2 rabl templates base, main, show for each controller

fixes #2600 - fixed gettext extraction on vms forms