Docker compatibility for mac (and likely windows too)

[blakeflei]

When running locally on mac (and likely windows too) none of the container ports are available. This is likely because there is no docker0 bridge on MacOS or windows. The workaround, described in the docs (same link as above) is to use the hostname host.docker.internal.

This hostname should also work on a linux host, provided the host is added via: `--add-host=host.docker.internal:host-gateway'. (moby/moby#40007 (comment), docker/for-linux#264 (comment))

[blakeflei]

Submitted PR 56