Fix flaky test: TimeoutTest

The discussion about the flickering test is present here - https://groups.google.com/forum/#!topic/mockito-dev/lDbmq9X622Y

Just as a reminder:

> Hey 
> 
> Build failed due to a fluke I think: 
> 
> org.mockito.verification.TimeoutTest > 
> should_try_to_verify_correct_number_of_times FAILED 
> 
>     org.mockito.exceptions.verification.TooManyActualInvocations at 
> TimeoutTest.java:71 
> 
> The test seems to be flaky? 
> 
> If someone can push DUMMY_COMMIT.txt to force the build and make it 
> green again; and take a look into the test and make it more stable 
> that would be most awesome :) 
> 
> Cheers! 
> -- 
> Szczepan Faber