Use metadata to make output more readable

[jabooth]

We currently don't use any of the metadata in making the output results more readable. As a simple example, the display_name_short metadata on methods would be an ideal candidate for use in CED legends and eventually on the website. Problems arise in using this in two areas:

1. Ensuring uniqueness. This is related to support custom modules in output dir #10. As we move away from predefined keys with guaranteed uniqueness to custom paths and arbitrary strings in metadata, we can run into situations where two methods for instance could have the same short name.
2. Reloading after failure. Currently CED plotting only depends on the output dir - the actual modules don't have to be present and loaded. This is nice and self contained. Currently no metadata is persisted to the output dir, so we would have to source and reload all original modules to plot output after the fact. Currently we allow relative paths in experiments to other modules, so although we have the original experiment we don't have the modules there to load.