[agent][go] Use new gommon/log

[at15]

There is new version of gommon/log https://github.com/dyweb/gommon/pull/28, which aims to provide better control over individual package, however, some project has to use it first before it can have a stable API. This burden falls to benchboard

• [x] logger for each package
• [x] logger for entire package
• [x] we may need dirty hack to sync gommon to vendor folder since we don't want to push to github then pull it down
  • [x] it seems we can remove the installed gommon in vendor folder and go will lookup in go path https://stackoverflow.com/a/44948118/

[at15]

actually ... I was heading in wrong direction by using sync_local, by default, go will lookup my workspace if it does not found the library in vendor ....

[at15]

now using dep and gommon/log is much more stable now