Introduce ILinkDiscovery as the base class from which ILinkDiscoveryService and ILinkDiscoveryListener are extended.  Introduce link types in ILinkDiscovery.  The link type is sent to all listeners.

Unit tests for the parts of device manager that should be working, and some effort at fixing compile errors in other modules

Added a REST API to get the list of storage source tables used by floodlight.

Fixed JUnit tests.

Conflicts:

	src/main/java/net/floodlightcontroller/util/TimedCache.java