Adding annotations and did some clean up.

[BigBlueHat]

• Explain why test is skipped.
• Remove skipped test/req no longer in spec.
• Enable createVp in context property test.
• Link to text for section 1.3 Conformance tests.
• Link to text for section 4.3 Identifiers tests.
• Link to text for section 4.3 Types tests.
• Add note about not testing 4.5 name/desc.
• Link to text for section 4.6 Cred Subject tests.
• Link to text for section 4.7 Issuers tests.
• Link to text for section 4.8 Validity Period.
• Link to text for section 4.9 Securing Mechanisms.
• Link to text for section 4.10 Status.

[BigBlueHat]

@aljones15 @tminard I've been working my way through the spec adding these annotations to the code. They should be mostly up-to-date.

However, I'm wanting to pivot off of this baseline and refactor this test suite code a bit. It's currently painful to navigate it as the entire list of requirements is in on big bucket... So, once this is in, I plan to refactor, then return to annotating and sketching out what tests are missing.

[BigBlueHat]

@aljones15 if you're OK with this, I'd like to wait on doing the issuer.name and issuer.description test changes. I can make them part of #74 if you'd like--and likely move them into the currently skipped name and description test section. We can then discuss with others where else to run the name and description tests. Issuer seems like a good candidate (and they're already written), but we can certainly discuss testing them in credentialSubject as well (if/when present, of course).

But...I'd love to get this one merged before dealing with that larger move (and base it on #74's new groups).