Closes #2261
Closes #2262
Closes #2386

When following error message is shown, then it will get converted to the
correct Exception classs of NotNullConstraintViolationException:

  PDOException: SQLSTATE[HY000]: General error: 1364 Field '...' doesn't have a
  default value

Added parameter "default_dbname" to pdo_pgsql driver which can be used to override the default database

PostgreSQL allows the user to set the application_name is connecting
to database. It is useful for monitoring purposes.
Currently one could just manually add 'application_name=foo' to DSN,
but having a parameter eases setting it using DoctrineBundle.

fix usage of PDO::PGSQL_ATTR_DISABLE_PREPARES for pdo_pgsql extension setups not built from PHP core

fixes #2249

it is best practice to implement retry logic for transactions that are aborted because of deadlocks or timeouts. this makes such method available inside the DBAL and also add detection for errors where retrying makes sense in the different database drivers

Features and changes:
* jsonb can be used with: options={"jsonb"=true}
* OVER is no longer reserved
* LATERAL is now reserved

Fixes #402 (https://github.com/doctrine/DoctrineBundle/issues/402) by connecting by default to 'template1' instead of the database with the same name as the user (Postgre default in case of no dbname).

Add support in fetch for type PDO::FETCH_OBJ