Stop the container after a specific timeout

[groovytron]

A user should only ask to start and stop an application.
Now an administrator will register the Docker images in the database, and could for example update the version of the image or even delete the image from the DB. In this case, it's better to do nothing, simply ensure that users cannot start an application whose image has been deleted or updated.
Eventually, the user or a timeout (we should probably also introduce this concept) will stop the running container and no more users will be able to use similar containers.