A better log format

[raullenchai]

Consider lighthouse's log format

[guo]

just one line change like this: https://github.com/rs/zerolog#pretty-logging

Example:

[dustinxie]

the current json output is for purpose of ELK processing, if we want a better console output, need to make sure does not break ELK functionality (like still outpu json to log file, but print out a better format to console)