pipeline: new packet framework logic

The Packet Framework pipeline library provides a standard methodology
(logically similar to OpenFlow) for rapid development of complex packet
processing pipelines out of ports, tables and actions.

A pipeline is constructed by connecting its input ports to its output ports
through a chain of lookup tables. As result of lookup operation into the
current table, one of the table entries (or the default table entry, in case
of lookup miss) is identified to provide the actions to be executed on the
current packet and the associated action meta-data.

The behavior of user actions is defined through the configurable table action
handler, while the reserved actions define the next hop for the current packet
(either another table, an output port or packet drop) and are handled
transparently by the framework.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Acked-by: Pablo de Lara Guarch <pablo.de.lara.guarch@intel.com>
Acked by: Ivan Boule <ivan.boule@6wind.com>