core: add clusterEmulatedMachines config values

Add the new clusterEmulatedMachines config value

Upgrade all cluster with the old config value EMulatedMachine

Bug-Url: https://bugzilla.redhat.com/927874
Change-Id: Icb035879bd2a25ecba72ac7691aaddcd9581e11a
Signed-off-by: Roy Golan <rgolan@redhat.com>