Look for Java 8 virtual extension methods annotated as tests.

Started discussion on the mailing list: http://groups.yahoo.com/neo/groups/junit/conversations/topics/24441

I don't think this is quite ready yet. I'm looking for feedback on whether it's ok to modify the default test runner, or whether there ought to be a new Java 8 test runner. I'm also looking for feedback on the testing strategy. Right now the new test is the only one that requires Java 8. Should it go in a separate module?