update vendors and adjust to seo bundle changes
since burgov/key-value-form-bundle became an optional/dev dependency of seo-bundle, it should be included in the composer.json on this level of the project
Merge pull request #256 from Burgov/prepare-rc

Fix error in AppKernel.php
use correct translation domain for seo content breadcrumb
updating dependencies
Merge pull request #255 from symfony-cmf/prepare-rc

update vendors and adjust to seo bundle changes