Changes to rest API in debugEvents to prepare for CLI

...va/net/floodlightcontroller/core/internal/Controller.java

.../java/net/floodlightcontroller/debugevent/DebugEvent.java

src/main/java/net/floodlightcontroller/debugevent/Event.java

...t/floodlightcontroller/debugevent/IDebugEventService.java

...a/net/floodlightcontroller/debugevent/NullDebugEvent.java

...oodlightcontroller/debugevent/web/DebugEventResource.java

...ntroller/linkdiscovery/internal/LinkDiscoveryManager.java