Added the ability for admin users to CRUD all node templates.
Node templates are now fully RBAC enforced. Old node templates
will be cloned into 'cattle-global-nt' namespace. Old node
templates will be deleted. Prior, node templates were in
creator's user namespace. This caused node templates to be
deleted when the user was deleted. Now, node templates can
persist when the creator is deleted and live in a global
namespace dedicated to node templates.