Add getName on blocks for SonataPageBundle

[jordisala1991]

Subject

I am targeting this branch, because this is BC.

Closes #1962 .

Changelog

### Added
- Added name for blocks so they can be recognized on SonataPageBundle.

[jordisala1991]

@haivala does this fixes your issue?

[VincentLanglet]

This method was deprecated from the interface https://github.com/sonata-project/SonataBlockBundle/blob/b161b8273366bec8d878e8e5a5c91a270eba3aa2/CHANGELOG.md#deprecated-2

So it require a NEXT_MAJOR to remove them in master. (And I don't know how it will be handle by the PageBundle)

[jordisala1991]

This method was deprecated from the interface https://github.com/sonata-project/SonataBlockBundle/blob/b161b8273366bec8d878e8e5a5c91a270eba3aa2/CHANGELOG.md#deprecated-2

So it require a NEXT_MAJOR to remove them in master. (And I don't know how it will be handle by the PageBundle)

Added NEXT_MAJOR comment. On SonataPageBundle 4.x it will be handled using https://github.com/sonata-project/SonataMediaBundle/blob/master/src/Block/FeatureMediaBlockService.php#L104-L109
already implemented on all blocks.

[haivala]

@haivala does this fixes your issue?

Yes! Thank you!