Add mdns module
add API getDeviceDiscoveryService
clear original db contents
Data-wangyu: clear db file
Merge pull request #209 from wangyufish/Data

Data wangyu->yuanzhe
add module socket.io-client
Complete device discovery service test
Merge pull request #210 from v11985/data2_wangfeng

Data2 wangfeng ->yuanzhe
contacts写入数据库bug未完成
fix
Merge branch 'data2' of ssh://github.com/IbpTeam/demo-rio into data2_xiquan
Merge pull request #212 from huyuanzhe/data2

Data2#153 yuanzhe->Wangfeng
test closure
Clean code
Merge pull request #213 from v11985/data2

Clean code ->yuanzhe
修改addData和initGit逻辑
Merge pull request #215 from shuanzi/data2_xiquan

Data2_xiquan->wangfeng
merge