Container config

@phamann @sndrs @gklopper 

Containers are now defined in a Scala config. This should allow us to easily add containers with multiple slices.

TODO: I'm going to make a separate pull request that will automatically write the fixed container IDs to the JavaScript file consumed by Facia Tool, so that we will no longer have to add them in both places.
Good - did not like this `Some("...")` business