Ensure that documents that drop data throw errors

[msporny]

To ensure JSON compatability, JSON-LD Processors preserve what they can when processing JSON. This can result in some information, that cannot be interpreted given the context provided, being dropped. While this doesn't happen for things using the VC 2.0 context, it can happen if other contexts that don't have a default vocabulary defined are used. JSON-LD processors do create warnings when when things like relative URLs are created or objects are dropped from JSON-LD because they don't have term definitions. We want to ensure that security specifications throw errors when these things happen (when pieces of information would not be signed). Additionally, we want to force the base URL to be null so signing operations on URLs will get same result as someone running it on a document parsed from a URL on the web.

[msporny]

PR #139 has been raised to address this issue. This issue will be closed once that PR is merged.

[msporny]

PR #139 has been merged, closing.