fixed no default locale exists
added helper to generate alternate link tags
added helper function to generate seo meta tags
Merge branch 'develop' of git://github.com/sulu-cmf/sulu into feature/href-twig-helper
fixed code style
Ask confirmation before deleting referenced snippets
fixed testcase
fixed #532
fixed get languages for node
Merge pull request #538 from sulu-cmf/feature/href-twig-helper

Implemented meta twig helper
Merge pull request #511 from sulu-cmf/snippet-delete-reference

Snippet delete reference
Updated changelog