Bug fix and PDO now returns errors

MongoDbIdQuery now extends the AbstractIdQuery, which in turn makes sure
the IdQuery interface is implemented.

Default is now for PDO to return SQL errors, should be configuarable,
but for the future
Change how the loader works

Warning the loader now works in a different way, old versions worked in
an other way!

Upfated the readme with the new loader settings

Loader changes:
- loaders are now even more abstract, only the seperator is build in the
prefix/namescape loader

Prev
- dir + namespace = path
Now
- dir + (namescape - leader) = path
* leader = the key that is used to register the path

Example:
'Pnatter' => 'PATH/TO/PNATTER',
The leader here is Pnatter

With this update you can better change directories for individual
(sbub)namespaces/prefixes
Bug fixes

PHPUnit bootstrap
- changed so the loaders work again

AbstractDb
- it isn't needed any more to "connect", using the getConnection now
sets up the connection. This makes sure the connection is setup when it
is needed
Locator now has ArrayAccess

Locator
- implmentes ArrayAccess
- extends ArrayObject

Test not validate