* 2.8:
[Serializer] Fixed throwing exception with option JSON_PARTIAL_OUTPUT_ON_ERROR
Tweaked some styles in the profiler tables
[Security] Fail gracefully if the security token cannot be unserialized from the session
[Form] AbstractLayoutTest - fix DOMDocument casing
bumped Symfony version to 2.8.34
updated VERSION for 2.8.33
updated CHANGELOG for 2.8.33
bumped Symfony version to 2.7.41
updated VERSION for 2.7.40
update CONTRIBUTORS for 2.7.40
updated CHANGELOG for 2.7.40