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
Fix jubatus servers to stop mixer before RPC server stopped

fixes #730
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
Use JUBAUTS_PLUGIN_PATH environment variable to load plugin
Merge pull request #732 from jubatus/fix-730

Fix jubatus servers to stop mixer before RPC server stopped
Add virtual dtor to clustering::storage
Add invalid_parameter exception
Add validation of configurable paramater
Add tests
upgrade gtest to 1.7 and show stderr for failed tests (fix #726)

Patch proposed to upstream in https://github.com/tanakh/waf-unittest/pull/9
use absolute path for the values of get_status (fix #634)