add stub to PHPUnit Test listern required to use master
Add DateTime override test, make it possible to remove override

Just adding the new test made
testWakupMagicIsNotMockedToAllowSerialisationInstancehack() fail, as the
override for internals is stored in config, not the container.

- made it possible to remove these overrides
- also added an explicit test for this behavior
PHP 5.3 support for testCanCreateNonOverridenInstanceOfPreviouslyOverridenInternalClasses
Real PHP 5.3 compatibility
Merge pull request #252 from fredemmott/datetime-override

Datetime override