Adding multipart learning switch

- improved logging
- wrapped simple implementation
- tidying up names
- fixed stop
- limited to IPv4 traffic
- fixed expire times (=0) for flow forwarding packets to controller
- Introduced InstanceIdentifier utility class.
- Separated utility functions to thematic classes.

Change-Id: I20bfb99797294767fbb0e290089cb2c701876ff4
Signed-off-by: Michal Rehak <mirehak@cisco.com>
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>