Merge pull request #10 from zhuzhaolong/Kenshin:dev

update readme
add basic cache
Merge pull request #11 from zhuzhaolong/Kenshin:dev

add basic cache
update metric cache data structure
Merge pull request #12 from zhuzhaolong/Kenshin:dev

update metric cache data structure
rurouni write to file
fix typo
Merge pull request #13 from zhuzhaolong/Kenshin:dev

rurouni write to file
统一 kenshin 模块对外接口
restore cache structure from file
add lock to MetaData
Merge pull request #14 from zhuzhaolong/Kenshin:dev

处理一些细节
add query protocol for MetricCache
add pickle receiver
delete tmp file