Initial vRouter/DPDK commit:
- initial support for MPLSoGRE
- dp-core: userspace btable
- dp-core: shared memory instead of /dev/flow
- dp-core: DPDK ports support
- utils: DPDK ports support

Authors:
  Maciej Czekaj <mjc@semihalf.com>
  Grzegorz Bernacki <gjb@semihalf.com>
  Andriy Berestovskyy <aber@semihalf.com>
  Michal Dubiel <md@semihalf.com>
  Kamil Rytarowski <kamil@semihalf.com>