Nailgun should serialize DPDK related info into astute.yaml

`astute.yaml` should be extended as following

::

  network_scheme:
    transformations:
    - action: add-br
      name: br-prv
      provider: ovs
      vendor_specific:
        datapath_type: netdev
    - action: add-port
      name: enp1s0f0
      bridge: br-prv
      provider: dpdkovs
      vendor_specific:
        driver: igb_uio
  dpdk:
    enabled: True
    ovs_core_mask: 0x4
    ovs_pmd_core_mask: 0x6
    ovs_socket_mem: 128,128,128,128