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

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 charset option for pdo_pgsql driver

- Fixed docblocks
- Removed return statements on void methods
- Cleaned up unused private / local variables
- Fixed license issues
- Removed SVN leftovers
- Fixed doctrine-project.org links
- Added line breaks before return statements

[2.0] More general work on the SchemaManager and Platform classes. Making API more complete and adding sqlite and mysql test coverage.