baseimage: Remove code for dealing with envvars from my-init
baseimage: Remove code for dealing with SSH keys from my-init
cli: Document `devstep run` command and make it use DEVSTEP_HACK_RUN_OPTS
baseimage: Skip /etc/container_environment creation since we are not using it
baseimage: Fix annoying "fail: /etc/service/*: unable to change to service directory: file does not exist" message

Fix GH-14
cli: Implement `ps` and `images` commands
docs: Small improvements to the index page