Merge into master from pull request #3791:

...floodlightcontroller/core/IFloodlightProviderService.java

...main/java/net/floodlightcontroller/core/OFSwitchBase.java

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

...loodlightcontroller/core/internal/EventHistorySwitch.java

...va/net/floodlightcontroller/core/web/CoreWebRoutable.java

...troller/core/web/EventHistoryTopologyClusterResource.java

...controller/core/web/EventHistoryTopologyLinkResource.java

...ntroller/core/web/EventHistoryTopologySwitchResource.java

...r/linkdiscovery/internal/EventHistoryTopologyCluster.java

...ller/linkdiscovery/internal/EventHistoryTopologyLink.java

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

...main/java/net/floodlightcontroller/util/EventHistory.java

...a/net/floodlightcontroller/util/EventHistoryBaseInfo.java

...htcontroller/util/EventHistoryBaseInfoJSONSerializer.java

...et/floodlightcontroller/core/internal/ControllerTest.java

.../floodlightcontroller/core/internal/OFSwitchBaseTest.java

...loodlightcontroller/core/test/MockFloodlightProvider.java