Fixed Seo Twig Extension

- Replaced deprecated Twig features
- Introduced safe html escaping
- Changed echo to return
Fix facebook share button widget

According to the [Facebook documentation](https://developers.facebook.com/docs/plugins/share-button) layout settings must be configured with `data-type` HTML5 attribute
Fix block_twitter_share_button.html.twig
fixed tests
Merge pull request #58 from polem/patch-1

Fix facebook share button widget
Merge pull request #60 from polem/patch-2

Fix block_twitter_share_button.html.twig
Merge pull request #57 from WouterJ/patch-2

Fixed Seo Twig Extension
Merge remote-tracking branch 'sonata-project/master'