Enhance configuration processing - eliminate post

Alter the retrieval of the Kea configuration to be a background submission as is done in each validation step. This will allow showing a new div with the configuration in some sort of textarea with scrollbars. Ideally, this textarea should have a javascript method to copy the content, though this isn't strictly necessary.

The current behavior is to post and receive an extremely simple html response with the configuration only... no navigation buttons or etc...