[Thinkit] Add a test case for ip2me packets.Use constant instead of string literals. Add detailed counter data in sFlow inband TestInbandPathToSflowCollector test. Dump p4 table entries in test teardown method. Disable Ip2me test. Add a log of the picked port. Rename StartSflowCollector to RunSflowCollectorForNSecs.

[Thinkit] Add a test case for ip2me packets.Use constant instead of string literals. Add detailed counter data in sFlow inband TestInbandPathToSflowCollector test. Dump p4 table entries in test teardown method. Disable Ip2me test. Add a log of the picked port. Rename StartSflowCollector to RunSflowCollectorForNSecs. #4217