Restore logging for outside usage like engines

Restore logging for outside usage like engines, @gitterhq/faye-redis

I wanted to npm link and debug this module and found that other places like the engine were using server.error(...) to log things but were just erroring out without these changes. We currently don't see this problem in production because the commit that removed the logging hasn't shipped in a release yet.

Created during https://gitlab.com/gitlab-org/gitter/webapp/merge_requests/1146