add cpu dockerfile

[thetechnocrat-dev]

Not sure if this is helpful, but the following commands worked from the project root for me using this branch

$ docker build -t equibind_cpu -f cpu.Dockerfile .
$ docker run -it equibind_cpu bash

If this useful I can clean up the file and do a multistage with the GPU Dockerfile to make maintaining easier.

Also, let me know if there are any test commands I can use inside the Docker container.

[kjwallace]

@NiklasTR merge plz

[NiklasTR]

Hi team - @McMenemy and @kjwallace is this ready to be merged?