Refactor Horde_Db test suite.

This was completely broken after the recent Horde_Test_AllTests changes.
The Google driver is no more.
Fix tests after Horde_Test refactoring.
Move _handleNotifications() to base class.
Fix ctor signature.
Workaround different passed arguments.
Fix test_framework after Horde_Test refactoring.
Specify test script, only notify myself for now.