Merging the postgres container back into the api container (simpler

Merging the postgres container back into the api container (simpler
and more consistent with best practices).

'docker build -t arvados/api api' now builds a container with postgres
and apache2, and installs the API Rails database.

To have this container start multiple services at run time
(i.e. postgres + apache2) the popular solution is to make supervisord
the entrypoint for the container.