Implement initial vDL test suite

[msporny]

The following items need to be done to implement the initial vDL test suite:

• Create initial vDL @context and publish to w3id.org.
• Import relevant parts of vaxcert test suite to this test suite.
• Create generator that generates DLs for all 50 US States.
• Determine which issuers/verifiers to use (notify companies that have failures of any kind).
• Write test suite ensuring that it can run in parallel.

[aljones15]

WRT to issuers and verifiers:

1. None of the verifiers were 100%
2. Factom had the best verifier (able to verify 4/6 VCs sent to it)
3. Dock failed every verification
4. measuro.io and trasmutes VCs were verified by the most verifiers
5. I probably am missing the most up to date issuers and verifiers
6. SICPA failed everything (probably a bad endpoint)