add catching exceptions
implements set_config and get_config with zookeeper.
jubaconfig is a command line tool that set/get config data from zookeeper.
don't use not statement
Merge branch 'develop' into feature/zkcommand

Conflicts:
	src/common/membership.cpp
	src/common/wscript
	tools/generator/keeper_generator.ml
fix shortest_path when target is found before reaching landmark
msgpack-rpc based client merged
msgpack-rpc based rpc-server merged
implement set_config from file or zookeeper.

implement three functions as follow,
void config_fromlocal(const std::string&, pfi::text::json::json&);
void config_fromzk(lock_service& , const std::string& , const std::string& , pfi::text::json::json&);
void config_tozk(lock_service& , const std::string& , const std::string& , pfi::text::json::json&);
changed: server_helper::start() is template function.
Remove classifier_factory class and change create_classifier method to a normal method.

Conflicts:

	src/server/classifier_serv.cpp
Change classifier factory interface

Conflicts:

	src/server/classifier_serv.cpp
Remove regression_factory class and add regression namespace

Conflicts:
	src/server/regression_serv.cpp
fix to latest develop branch.

	modified:   src/classifier/classifier_factory.cpp
	modified:   src/classifier/classifier_factory.hpp
	modified:   src/classifier/classifier_test.cpp
	modified:   src/regression/regression_factory.cpp
	modified:   src/regression/regression_factory.hpp
	modified:   src/regression/regression_factory_test.cpp
	modified:   src/server/classifier_serv.cpp
add JSON to regression factory
changed: all server, keeper changed to msgpack-rpc base

+ changed: rpc_server2 accept pfi::common::function instead of
  mp::function to simplify server_util/server_helper.
changed: obsolate pfi-rpc based code
changed: rename msgpack-rpc based classes
fix regression namespace

jubatus::regression::hogehoge.
refactoring classifier namespace.

same as recommender, regression
add json to string function in util.cpp