Regression: a stuck SlimClient is no longer killed

In version 20130531, when the SlimService process did not properly close itself after receiving a 'bye', it would be killed.

In 20131110 (and git master HEAD), this is no longer the case.

While I do think this would be desirable behavior, the way it happened in 20130531 was not very nice either (it happened as a side-effect of the MultipleTestsRunner registering an exception). AFAICS the following change makes the code work as it was actually intended: the stuck Slim command will be killed by the SlimCommandRunningClient.