doctrine2/UPGRADE_TO_2_2

# Removed support for onUpdate in @JoinColumn

The onUpdate foreign key handling makes absolutly no sense in an ORM. Additionally Oracle doesn't even support it. Support for it is removed.

# Changes in Annotation Handling

There have been some changes to the annotation handling in Common 2.2 again, that affect how people with old configurations
from 2.0 have to configure the annotation driver if they don't use `Configuration::newDefaultAnnotationDriver()`:

    // Register the ORM Annotations in the AnnotationRegistry
    AnnotationRegistry::registerFile('path/to/Doctrine/ORM/Mapping/Driver/DoctrineAnnotations.php');

    $reader = new \Doctrine\Common\Annotations\SimpleAnnotationReader();
    $reader->addNamespace('Doctrine\ORM\Mapping');
    $reader = new \Doctrine\Common\Annotations\CachedReader($reader, new ArrayCache());

    $driver = new AnnotationDriver($reader, (array)$paths);

    $config->setMetadataDriverImpl($driver);