Removed the `Dbal` prefix from the class names and moved them to the `Doctrine\Tests\DBAL` namespace.

If you pass a null to the where array of update or delete it's
pretty obvious what you want.

Most (all?) databases won't match anything if you actually try
to compare with NULL making this a silent failure without it.

    Connection#insert(),  Connection#update() and Connection#delete(). Closes GH-271

Added a bunch of functional tests for the public read, write and transactional public DBAL API, passing all the current drivers

Added a Write Test