This makes standard use of shellcheck work without needing to provide extra configuration anywhere.
Also remove use of inline 'shellcheck disable' calls that are already defined in the .shellcheckrc and don't need to be set inline.
Due to how the nginx proxy implementation works, if an app has either many process types or many containers for a process type other than web, it is possible to see downtime on the web process due to the old web containers rotating out _before_ we reload the nginx config.
The correct fix would be to use some sort of dns-based resolution for the nginx config, but pending that change, we reload nginx twice now - ugh - to avoid this.
The link flag was previously not filtered _after_ fetching build args for dockerfile builds, which meant if a plugin exposed that in it's own docker-args-build trigger, it would break deploys.
Additionally, allow for whitespaces between link and volume flags.
