New major version with some breaking changes

Drop support for php 5.4
Removed$info->source and replaced by $info->feeds that returns an array of rss/atom feeds
Removed Embed::createSource() and all Embed\Sources\* classes
Removed the support for Guzzle 5
Changed the options array to a more simple structure.
Removed the Embed\RequestResolvers\* and Embed\ImageInfo\* classes and replaced by an unique Embed\Http\DispatcherInterface.
Improved speed avoiding some useless requests
Most code has been refactored to be more simple and clear.

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