ui: reduce describe depth, using recursive describe instead

Updates issue https://code.google.com/p/camlistore/issues/detail?id=319

Change-Id: Ie02b0f565c6ff4c9582cecc78914392a60bf9502
importer/foursquare: don't fetch images if we already have

Change-Id: Ib36e1b7337efa2bcd3de2aa038005b11225e05a8