Merge pull request #741 from jubatus/feature/unlearning

New feature: unlearning
Conflicts:

	jubatus/client/clustering_client.hpp
	jubatus/client/clustering_types.hpp
	jubatus/core/anomaly/light_lof.cpp
	jubatus/core/anomaly/wscript
	jubatus/core/classifier/classifier_test.cpp
	jubatus/core/classifier/wscript
	jubatus/core/driver/anomaly_test.cpp
	jubatus/core/driver/mixable_versioned_table.cpp
	jubatus/core/driver/mixable_versioned_table.hpp
	jubatus/core/driver/nearest_neighbor_test.cpp
	jubatus/core/driver/wscript
	jubatus/core/framework/linear_function_mixer.cpp
	jubatus/core/framework/push_mixable.hpp
	jubatus/core/recommender/nearest_neighbor_recommender.cpp
	jubatus/core/recommender/wscript
	jubatus/server/server/clustering_impl.cpp
	jubatus/server/server/clustering_proxy.cpp
	jubatus/server/server/clustering_types.hpp
	wscript