Refactor API code to use annotator-store flaskless

Everything seems to work: reading, creating, updating, deleting, searching, permissions seem to work but need better testing, and in general more tests and thorough code review would be good.

To keep a consistent style and make refactoring easier, I decided to use traversal with a `@view_defaults` class everywhere, using the defaults class to specify the `context` predicate, so as to group the views within that. For the same reasons I do not use view names but use a resource for each location (I explictly state `name=''` for clarity, though that could be removed). I think this style works out nicely.

I put some questions in the comments, just search for the question marks.

The dependency on the next (flaskless) annotator-store version has yet to be added.

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I know you didn't add the `IConsumerClass` type, but I find this whole pattern somewhat distasteful. The abstract `IConsumerClass` is implemented in exactly one place right now, and the added indirection it creates in (for example) `get_consumer` isn't worth it.

I'd rather we stripped `IConsumerClass` and just referred directly to `h.auth.local.models.Consumer` where needed.