SUREFIRE-428: integration test to check class path order

[Dan Fabulich]

Class path ordering is tricky, and changed recently.  Benjamin Bentmann 
provides a regression test in SUREFIRE-428.

However, I'm not certain if I should apply it in Surefire, because we use 
those integration tests to verify backwards compatibility with older 
versions of Maven.

My initial thought was that perhaps the test should be applied in 
core-integration-testing; there are a few small Surefire integration tests 
there (which I think is correct), and I think this could join them to 
prevent regression for MNG-3118.

Then again, since it's fundamentally an integration test, it doesn't 
specifically belong to either side, so maybe Surefire is the best place to 
install it...?

Thoughts?

-Dan