Support "advanced example" from JSON Schema

[philsturgeon]

Contains #2 also.

By adding more examples I'm able to find more keywords and discrepancies. This one particularly helped find an issue.

1. The root level id should be remove just like $schema is already.
2. dependencies will be switched to OpenAPI equivalent (thanks @handrews)

[handrews]

dependencies stuff looks good. Skimmed the rest, looks fine but did not go into detail on all of the example files.

How are you handling it when id affected how $ref resolved? Just removing id can leave that broken.

[philsturgeon]

I'll put that on the TODO @handrews.