Review validation gaps with BCO Validator API

[bentsherman]

The BCO project has a standard API endpoint for validation BCO manifests:

https://biocomputeobject.org/api/docs/

According to the BCO maintainers there are two minor issues with the current BCO manifest:

1. URIs for files in the description domain do not validate (suggest using something like file:///)
2. date-time doesn't appear to validate against the schema (is it ISO-8601?)

These issues should be reviewed and addressed as needed.