Get a warning for Nodev5

[jeid64]

I get a warning building the container that Nodev5 is out of date. I can look into updating to a new version possibly?

[dkorunic]

@jeid64 I went forth and overhauled the whole project (doesn't use root inside Docker, uses Compose, uses recent Ubuntu Xenial 16.04 LTS, updated docs, uses NodeJS 9.x etc.): https://github.com/dkorunic/slackbridge. Cheers.