Remove free_long and free_double
Fix code style
Write compressive storage test
Increment forgetting weight all of when carry up occurrs
Set forgetting_threshold in test
Merge remote-tracking branch 'upstream/develop' into remove_free

Conflicts:
	jubatus/core/clustering/kmeans_compressor.cpp
Remove unnecessary serialize method
Refactor
Use partial_sort
Merge pull request #704 from jubatus/fix-forget-weight

Fix behavior of forgetting_factor
Merge pull request #671 from jubatus/remove_free

Remove free_long and free_double