added type check
fixes edit select bug
Merge pull request #209 from sulu-cmf/hotfix/smart-content-tag-filter

[Hotfix] fixed tag filter for smart content
Merge pull request #208 from sulu-cmf/hotfix/null-object

[HOTFIX] Added type check when serializing smartcontent and internal links
Merge branch 'master' of git://github.com/sulu-cmf/SuluContentBundle into develop