[GH-337] Removed dependency on common as required by dbal anyway

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

Url: https://github.com/doctrine/doctrine2/pull/337

Message:

Not sure if this is the way to resolve this problem or not but I just tried to install dev-master using composer, doctrine/dbal and doctrine/common are both required in the "dev-master" versions but doctrine/dbal requires doctrine/common: >=2.2.0,<=2.2.99 which causes a conflict. Removing the dependency on doctrine/common would allow doctrine/dbal to install the version it requires. If this is not an ok solution then is there an alternative one?