Changes to permit keep_server containers to authenticate to api_server.

* Generate an API "superuser token" and deliver this token to the
  Keep server via warehouse.conf.
* Start the keep_server containers with a link to api_server.
* Add config.yml to the dependency chain for the base image (so it will
  be rebuilt if PUBLIC_KEY_PATH is changed).
Mount separate volumes for each keep container launched.
run.sh bug fixes.
API_SUPERUSER_TOKEN must be named API_SUPERUSER_SECRET to be autogenerated.
Superuser script must be run as ./script/create_superuser_token.rb.
Add support for ARVADOS_API_PORT.
run.sh prints instructions/settings for running a test suite.
Reorganized code to support 'start' command.
run.sh: add "stop" command, also remove old containers before trying to start them
run.sh: bug fixes
Added 'test' command to run.sh.
Adding 'run.sh test api' to run API server Rails tests.
Merge branch '1587-fix-test-suites-in-devsandbox'