Apply feedback on validation interface

[OR13]

cc @tsnyder-gs1us

[OR13]

@tsnyder-gs1us thanks for your feedback.

I've revised the interfaces to validation based on your comments, but due to the open ended nature of the W3C specs, I've had to make a few adjustments.

1. I eliminated the top level valid state, this is because when you move beyond revoked or suspended... its not clear what valid means.

2. I have disconnected the schema validation and status checks from the concept of "verified"... verified just means "not tampered with", it does not imply that the schema is valid

Have a look and let me know what you think.