This adds the API call to return all fields for a single layer3domain.
This should serve as a nice basis for other parts to be implemented.
All fields are put together into a single json document, merged together
with the other attributes of the table and then returned to the
requester.
This is the first draft of creating layer3domains and
ipblocks/containers.
This allows some testing with different things, like list building for
complex container output, but also how containers should behave.