[Go] project directory layout and etc.

Reference:
https://github.com/golang-standards/project-layout
https://blog.golang.org/v2-go-modules

Publishing v2 and beyond:

e.g v2 directory

github.com/googleapis/gax-go/v2

Go for Industrial Programming:
https://peter.bourgon.org/go-for-industrial-programming/
Optimizing for mean time to recovery (MTTR) instead of mean time between failure (MTBF).



Mitchell Hashimoto - Advanced Testing with Go:
https://www.youtube.com/watch?v=8hQG7QlcLBk



How you name your variable:
https://talks.golang.org/2014/names.slide
https://golang.org/doc/effective_go.html#names
https://blog.golang.org/package-names
https://rakyll.org/style-packages/ (No plurals on package naming)



Code review comments:
https://github.com/golang/go/wiki/CodeReviewComments