Brocade Vyatta VPN service and device drivers

Spec for introducing Brocade Vyatta VPN solution using new vendor specific
service and device drivers for Neutron

Implements: blueprint brocade-vyatta-vpnaas-plugin

Change-Id: I8a30cacaeb6c906d6deca8b49f38d224e4746e25
Merge "Brocade Vyatta VPN service and device drivers"