[FlickrBridge] Fixed broken bridge
[FlickrBridge] Fixed broken bridge

Following changes in the JSON data and selecting images for the
content (320x240 or bigger) and enclosure (largest version). All of
the data is now extracted from the JSON data instead of parsing the
DOM.

References #754

teromene/rss-bridge,Riduidel/rss-bridge,RSS-Bridge/rss-bridge,sebsauvage/rss-bridge,kranack/rss-bridge,teromene/rss-bridge,kranack/rss-bridge,RSS-Bridge/rss-bridge,Riduidel/rss-bridge,Riduidel/rss-bridge,ORelio/rss-bridge,kranack/rss-bridge,Frenzie/rss-bridge,ORelio/rss-bridge,ORelio/rss-bridge,simonbru/rss-bridge,RSS-Bridge/rss-bridge,Frenzie/rss-bridge,simonbru/rss-bridge,kranack/rss-bridge