Upgrade (or start anew with) everything

[duffn]

Driven by this comment: slack-ruby/slack-ruby-bot-server#153 (comment)

I started by upgrading all gems, then starting the server and going through error by error and trying to fix them, but this may not be the right path. This would be jumping Rails 3 major versions and also trying to work with deprecated packages like sprockets-coffee-react https://github.com/jsdf/sprockets-coffee-react

I got through adding WEBrick, fixing spring config, adding required manifest.js file, then ran into an issue with sprockets-coffee-react and stopped.

Perhaps this just requires a brand new Rails installation and then attempting to port over code to current implementations?