Input box for json.facet and json query in Admin UI

We need an input box for JSON facet. I imagine to add another text-box that appears when you click the "facet" checkbox in the Query tab of the Admin UI. Alternatively it could be a separate checkbox for "JSON facet".

The text box should be several lines high to facilitate easy copy/paste of JSON.

Also, add a text-box for "json" request param.