Report first Exception caught in TestRunner

In particular when testing with the Arquillian Persistence extension it can be very difficult to diagnose problems in a test:
Usually when seeding of the database fails some other After event listener fails as well, e.g. evaluation of @ShouldMatchDataSet.
Then Arquillian only reports the last error that the actual result differs from the expected one.
This makes fixing the test very hard.

This PR changes the JUnitTestRunner so that it keeps the first exception that passes by ExpectedExceptionHolder.testFailure() instead of the last one.