DriverRegistry is executed second time.
Also, initialize the driver before registering different blueprints,
which uses those driver inside them.
Thanks Khushboo for reporting the issue.
server connection.
The BaseDriver and BaseConnection are two abstract classes, which allows
us to replace the existing driver with the currently used. The current
implementation supports to connect the PostgreSQL and Postgres Plus
Advanced Server using the psycopg2 driver.
