feat(services): start services using Homebrew on OS X

This is one of several steps towards making the OS X and Linux environment more similar.

This still needs to be updated more to use the right service names on OS X (I also need to pre-install the services that should be pre-installed), but I figured I'd start the discussion by showing some code.

@svenfuchs I think you were working on something to extract starting services into a Bash script? Maybe it would be a good idea to wait until that's merged.