Add burst detection system (WIP)

This version contains many bugs, many bad designes, and few tests;
so we must brush up.
Merge branch 'develop' into feature/burst

Conflicts:
	jubatus/core/driver/wscript
	jubatus/core/wscript
	jubatus/server/server/wscript
Modify burst IDL
Regenerate
Modify burst_serv
Modify burst conf
Disable logging on add_documents when successed
Fix add_document to return count of processed document
Regenerate
Add set_diver
Cosmetics
Add bind_child_watcher
Detect another node added or removed in burst_serv
Implement rehashing keywords
Remove unnecessary logs
Fix burst IDL
Remove st_ prefix from burst.idl
Rename batch's one-charactor parameter
Regenerate
Fix burst_serv