[GH-280] Use int values instead of strings for PostgreSQL booleans

This issue is created automatically through a Github pull request on behalf of chEbba:

Url: https://github.com/doctrine/dbal/pull/280

Message:

1. 1. The Problem:
      The current implementation for PostgreSQL uses strings 'true' and 'false' which are not working with PDO::ATTR_EMULATE_PREPARES.

1. 1. Solution:
      Use ints like in the default platform implementation.

1. 1. Comments

• Tested only on my local php 5.4.9
• Fixed NamedParametersTest to use int columns instead of strings (does not work with PDO::ATTR_EMULATE_PREPARES when compare string column IN array of ints)
• Fixed DbalFunctionalTestCase sql parameters dumping (found while fixing NamedParametersTest)
• Added support for driver options configuration via phpunit config globals