Create a CWL workflow that creates an annotation bundle

[chrisamiller]

The steps are well documented here:
https://github.com/genome/analysis-workflows/wiki/Gathering-input-files

Automating it would go a long way towards making creation easier, both internally, for version upgrades, and for external users.

This would also potentially enable us to pass around a single "annotation_bundle_directory", thus massively simplifying the inputs for some of the workflows (potential future goal - there are pros and cons).