Updated vendors
Merge pull request #1 from pkruithof/update-vendors

Updated vendors
Removed PHP 5.4 support
Merge pull request #2 from pkruithof/update-vendors

Removed PHP 5.4 support
Updated lock file
Merge pull request #3 from pkruithof/update-vendors

Updated lock file
Implemented Doctrine serializer
Merge pull request #4 from pkruithof/doctrine-serializer

Implemented Doctrine serializer