Fix jenerator for jubatus_core
add log4cxx-based logger (refs #746)
replace from_data with from_datum to be consistent with recommender (fix #564)
add config for nearest_neighbor_recommender
add light_lof config
Merge pull request #804 from jubatus/fix-jenerator

Fix jenerator for jubatus_core
Merge pull request #809 from jubatus/fix-564

Replace *_from_data with *_from_datum (server layer)
improve logger to provide feature like glog
use glog-like log syntax without configuration
method signature improvements and style fix
fix typo
Merge pull request #807 from jubatus/add-logger

add log4cxx-based logger (refs #746)
migrate from google-glog to log4cxx-based logger
add log4cxx sample configuration file
add liblog4cxx to pkg-config dependency
add liblog4cxx10-dev to travis config
fix logger to abort on FATAL log
Fix grammatical errors.
fix include headers and pass cpplint
fix travis config to use proper branch