Add support for twitter:image meta in OpengraphResolver
Use DOM and browser parser to parse tags
Imgur Album resolver : support /gallery/ urls
FlickrResolver: return Large or Original format
Revert "Imgur Album resolver : support /gallery/ urls"

This reverts commit d18930e7ef3c17ccb83579b69b335547ac96fe32.
inverted twitter:image and og:image

As most of the time the twitter:image is bigger than the og:image (check the official specifications), is better to check for the twitter card image before the tiny facebook one.
Instagram plugin : support instagr.am short URLs
Remove useless file
Improve OpenGraph resolver

When sites use both OpenGraph and Twitter cards meta, use a scoring
system to determine the best image.
Also add support for ogp flavored twitter cards meta.
OpenGraph resolver : better score for twitter
Tag parser : return null if malformed tag
Opengraph : missing condition
WebPage resolver: add support for lazy loaded images
Update README
OpenGraph : add comments
Update demo
Merge branch 'master' into gh-pages
imgur : update albums URLs
Opengraph: todo