Add a config setting: auto_admin_user

This setting is optional, and can be configured to the The e-mail
address of the user you would like to become marked as an admin user on
their first login. This is useful during installation.

In the default configuration, authentication happens through the Arvados
SSO server, which uses openid against Google's servers. In that case
this e-mail address should be an address associated with a Google
account.
Improve Makefile rules.
Start Keep container from run.sh.
Fix dependencies.
Converted README to real markdown.
* Docker API container: add support for the auto_admin_user feature (API server).

This closes #1655

* Default WORKBENCH_INSECURE_HTTPS in config.yml.example to true,
  because we use self-signed certificates in the development environment.
Merge branch 'master' of git.clinicalfuture.com:arvados