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.
