add ability to set uo log output

[lvoby]

Is your feature request related to a problem? Please describe.
Add ability to set up logging output. We run project on google cloud and we use google log explorer for logging collection. When log appear in stderr it marks like severity:ERROR

Describe the solution you'd like
By default golang log write to stderr. To change output we can use log.SetOutput

Describe alternatives you've considered
I'm open for any other solutions, thanks