[2.0][DDC-284] Fixed. API polish and some convention over configuration simplifications for join columns and join tables.

[2.0] DDC-92 - Refactored Doctrine\DBAL\DriverManager some more in regards to exceptions and added some more test-cases.

[2.0] DDC-92 - Removed DoctrineException from Doctrine\DBAL\DriverManager and replaced with more specific DBALException's

[2.0] Implemented DQL bulk DELETE support for Class Table Inheritance. Other cleanups, refactorings and docblock additions.