Support newer versions of junit (>4.7)

JUnit4.7 introduced @Rule, that only wrapped the actual test method.
Newer versions wrap @Before and @After too, so @After in included in the
async task. Cleanup code isn't expecting that, so ends up running
before the test completes.

Fix this by filtering out the WorkflowTest rule from the rules that
Junit handles, and instead invoke it separately.
Reset the exception/timeout configuration for each test run.