models/search: Select all fields in searches

Issue #251.
views/download: Wrap results in preview-frame

Issue #251.
js/download: Import Stefan Goessner's json2xml

Issue #251.
js/download: Pettify XML output

Insert newlines and tab indentation.

Issue #251.
js/download: Implement XML format output

Issue #251.
js/download: Add 'available_at' attribute to data

Issue #251.