Merge pull request #4 from rsdy/master

[enh] add js to install on firefox as search engine
[mod] github ribbon to about page
[enh] about page updates
[enh] categories to request callback
[enh] piratebay engine added
[enh] displaying seeders/leechers
[enh] magnet link added
[enh] thumbnails to youtube video results
[enh] about page update
[fix] description escaping
[enh] result rendering templates
[enh] image result template added
[enh][mod] using image template rendering
[fix] skipping empty urls
[fix] debug print removed
[fix] image width
[fix] handling missing github descriptions
[enh] merging only results with same rendering templates
[enh] valid json content type
[fix] unused var removed