split 51_openvswitch-service.sh to 51_openvswitch-service-netfilter.sh 51_openvswitch-service-openflow.sh
refactor case statement.
ASHIBA_ENV -> VDC_EDGE_NETWORKING.
add VDC_HYPERVISOR parameter.
add VDC_HYPERVISOR parameter.
add kvm and lxc to VDC_HYPERVISOR.
update vmimage file name.
add VDC_HYPERVISOR to SETUP.