Provide the way to specify the strategy on instantiting AppllicationContext e.g. each test method or each test case

Currently the application context is being created once per test case and being destroyed afterwards by ApplicationContextDestroyer. First but all it would be better to have the application context created once per test case, but still in some situation it would be good to be able to run each tests with completly new ApplicationContext. So altogether it would be preferable to enable user the deicision on how the application context should be handled by the extension.