add clustering_test.cpp
revision should be initialized
add clustering_test.cpp
SetUp() in test should do SetUp repeatedly
parametized test must be used via TEST_P
add do_clustering() test
test `get_nearest_center`
add test for `get_nearest_members`
Use pair instead of shared_ptr of pair in test
Merge branch 'develop' into feature/test_clustering_driver
Change condition and write comment
Merge pull request #650 from jubatus/feature/test_clustering_driver

Test driver::clustering