[GH-200] ClassMetadataFactory child classes can now filter the metadata when calling getAllMetadata

This issue is created automatically through a Github pull request on behalf of theUniC:

Url: https://github.com/doctrine/common/pull/200

Message:

This is due mainly, because we have found performance issues when trying to generate a complete schema (annotation based) from a legacy database with tons of tables with the ConvertMapping command.

This will let filter table names to the ```Doctrine\ORM\Mapping\Driver\DatabaseDriver::getAllClassNames``` and ```Doctrine\ORM\Mapping\Driver\DatabaseDriver::loadMetadataForClass``` methods, and extract class metadata from a smaller subset of classes (I'm doing another PR for this in the ORM repository).