Improve getPath() functions in IRoutingService

Improve getPath() functions. Null is no longer returned anywhere. Instead, we use empty Path objects to indicate a path was not found.

fix concurrency issue in Statistics

Fix forwarding bug

Extract possible VLAN tag from packet-in's match

Allow retrieval of VLAN tag from packet-in match. The VLAN tag might be here if the switch popped the VLAN tag from the packet itself prior to encapsulating it in the packet-in message.

Check special ports using loxi, not using bitmasks

Improve Forwarding link/port down handler

Forwarding tweaks

Each hop of path should optionally ignore in-port in flow match

Add detailed-match property to Forwarding

Fix forwarding bug

Add new detailed-match property to define source and destination addresses to match on in each layer. Also add in-port as an optional match for the existing match property.

Fix utilization link costs

Next round of topology updates

Don't use statistics service to get link speed. This can be derived from the IOSwitchService more efficiently. Remove link speed function from IStatisticsService.

Major topology/routing improvements

Change log levels of frequent, unnecessary logs to debug. Were previously warn. Add new RoutingManager to properties