add twitter-json file

[MuyangLiu]

add simple json files for kvstore test.

[MuyangLiu]

new efile
1 2 {"event":"event_name","weight":8,"timestamp":"2018-05-16-17:212321"}
new vfile
1 {"name":"user_name","age":12,"phone":"13812345678","weight":2}

[yecol]

maybe this is sufficient for efile and help to reduce the size:
1 2 {"weight":8,"time":"2018-05-16"}