examples/flow_distributor: new example to demonstrate EFD

examples/flow_distributor: new example to demonstrate EFD

This new sample app, based on the client/server sample app,
shows the user an scenario using the EFD library.
It consists of:

- A front-end server which has an EFD table that stores the
  node id for each flow key, which will distribute the incoming
  packets to the different nodes

- A back-end node, which has a hash table where node checks,
  after reading packets coming from the server, whether the packet
  is meant to be used in such node, in which case it will be TXed,
  or not, in which case, packet will be dropped.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Signed-off-by: Saikrishna Edupuganti <saikrishna.edupuganti@intel.com>
Acked-by: Christian Maciocco <christian.maciocco@intel.com>