Also auto-generate _SECRET config variables when they are unset, like we
do for _PW config variables.
Merge branch 'master' of git.clinicalfuture.com:arvados
Bring the name of the workbench secret token config variable in line.
Add SSO docker container
Merge branch 'master' of git.clinicalfuture.com:arvados

Conflicts:
	docker/build.sh
	docker/config.yml.example
Generated files shouldn't have been committed.
Fixes for SSO rails app.
Let API server use SSO container.

This doesn't work quite yet - need to sort out inter-container
communication. But it's very close now.