Use new integrated ddl-sql-sync.

This should fix #416 as well as encourage code reuse and create the concept of ORM drivers.
ORM drivers will make it easier to build additional packages on top of ORM and eventually encapsulate database-engine specific functionality.
Eg: [locomote/node-migrate-orm2](https://github.com/locomote/node-migrate-orm2) which currently has to hack around these issues.

See node-sql-ddl-sync#12