Rename IOFSwitch HA role request interface and add unsupported exception

...floodlightcontroller/core/HARoleUnsupportedException.java

src/main/java/net/floodlightcontroller/core/IOFSwitch.java

.../net/floodlightcontroller/core/internal/OFSwitchImpl.java

...a/net/floodlightcontroller/core/internal/RoleChanger.java

.../floodlightcontroller/core/internal/OFSwitchImplTest.java

...t/floodlightcontroller/core/internal/RoleChangerTest.java

.../floodlightcontroller/util/OFMessageDamperMockSwitch.java