Add golang information to --version flag

@ayufan Can you make gitlab-ci-multi-runner to output information similar to docker version. This would make it easier to open issues - at least if it's a go issue.

% docker version
Client:
Version:      1.8.2
API version:  1.20
Go version:   go1.5.1
Git commit:   0a8c2e3-dirty
Built:        Mon Sep 14 12:09:36 UTC 2015
OS/Arch:      linux/amd64