Feature #2423 #2092: New generic HYBRID section in VMs, better automatic_requirements
ture #2423 #2092: Bug in VirtualMachine::get_hybrid_hypervisors
Feature #2423 #2092: Skip storage scheduling for hybrid hosts
Feature #2423 #2092: Add HYBRID=YES to ec2 probes
Feature #2423 #2092: Code cleanup.

Hybrid hosts are not detected with the generic HYBRID=YES
Feature #2423 #2092: Allow deployment to hybrid hosts using system DS -1