[WM] remove supervisor, SSH, & supporting stuff from base Dockerfile

According to this blog post, we shouldn't need SSH running in our containers:
http://jpetazzo.github.io/2014/06/23/docker-ssh-considered-evil/

There may still be some containers that need supervisor for other
reasons. If so, we can create a new intermediate container that installs that.

For the others, there is still work to do to move them away from
supervisor and towards running their primary commands
directly. I *think* we can just do that opportunistically as we touch
them for other reasons.
[WM] remove files that are no longer needed by the base container
[WM] add intermediate supervisor build

This is primarily for synapse containers that need >1 process running in
their containers.
[WM] reorganize JDK & clojure-api builds

We aren't really using the clojure-api build anymore, so I moved
clojure-api-build to clojure-api (it's a superset, so it shouldn't break
anything; it just installs leiningen). I also based it on the new
oracle-jdk-7-supervisor base image (see below).

I renamed oracle-jdk-7 to oracle-jdk-7-supervisor and based it on the new
supervisor container (since we're trying to remove that from the base
container). We need both Java and supervisor in the synapse-using containers, so
the options are 1. create a new base container w/ both or 2. install one of
them in every downstream container that needs both. I've opted for #1.
[WM] update the README with new repo names
[WM] rework docker image tree along agreed-upon lines
[WM] move supervisord.conf to clojure-api-supervisor & delete old supervisor build
[WM] update README again to reflect latest base image hierarchy
Merge pull request #4 from turbovote/stop-doing-it-wrong

remove supervisor, SSH, & supporting stuff from base Dockerfile