DockerMachineStrategy does not work

DockerMachineStrategy DockerSource startup works, since commands can be forwarded over DockerMachine. However, attempts to return a valid IP:Port mapping to allow connections does not work. This is a result of DockerMachine delegating container subcreation to the existence of a physical virtual machine (where physical refers to an outside provider, like VirtualBox or Azure and not the physical presence of a machine), which makes exposing ports dependent on the type of virtual machine used. Therefore, it is impossible to return an accurate IP:PORT combination of the docker-machine because the PORT given will most likely not be mapped to anything on the physical machine.

As a result, DockerMachine support will be dropped.

Start by locating DockerMachineStrategy and DockerSource, then inspect how startup commands and IP:PORT mappings are handled. Remove DockerMachine support consistently, and verify that DockerSource startup remains usable without claiming an accurate mapping; the issue names no tests or files to run.

Written by the indexing model from the issue text.