[2.0] DBAL cleanups (DDC-46). Proxy class improvements (DDC-19, DDC-39). Started new UPGRADE_TO document for upgrade instructions between advancing Doctrine 2 versions.

[2.0] Accomodate joincolumn names in the metadata, in the selection and the hydration processes. Improved Api of the ProxyFactory. Working implementation of lazy loading for *-to-one associations (affects #2348)

[2.0] Moved cache drivers to Common package. Added new annotation parser implementation to Common package. AnnotationDriver in ORM not yet migrated.

[2.0] Refactored cache drivers. Made use of ArrayCache as the metadata cache during a test suite run.