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

Transferred over all of the Yen's algorithm additions. This includes getRoutes(). Some additions may have been missed.

Fix bug in statistics module REST API to correctly retrieve requested statistics for given DPID and port.

Add link speed to statistics REST API, which might be useful to gauge how much of the available bandwidth is being used.