Port forwarding

[TimWillard]

This may already be completed due to the sidecar services issue (#9), which had the container use host networking

[TimWillard]

This is confirmed not working on Docker4Mac when the host machine attempts to access something running inside the container (i.e. the common act of going to localhost:3000 in Chrome to see a dev site).

This does not appear to have a clean solution.
One idea was to have the users go to a separate bridge (i.e. go to envy:3000 in Chrome) but the hypervisor that is being used to run the linux VM doesn't appear to expose an ip address of any kind. All communication goes through a socket: https://stackoverflow.com/questions/41267305/docker-for-mac-vm-ip. Maybe we could create a new bridge and bind it to the socket somehow (the stack overflow post suggests that socat can bind a localhost port to the socket with socat TCP-LISTEN:2375,reuseaddr,fork,bind=localhost UNIX-CONNECT:/var/run/docker.sock, maybe we can do something similar but more broad?)

Otherwise, we have to make the maintainer list ports in the config file, and there is going to be disparities between Mac and Linux versions (for example, the maintainer may forget to bind a port, which will work fine on Linux but cause problems on Mac).