Fixed part of the seg fault described in bug 9356 by cleaning reference counting on MultiAioCompletionImpl

Signed-off-by: Sebastien Ponce <sebastien.ponce@cern.ch>
Fixed part of the seg fault described in bug 9356 by adding reference counting on RadosReadCompletionData

Signed-off-by: Sebastien Ponce <sebastien.ponce@cern.ch>
Fixed remaining part of the seg fault described in bug 9356 by adding reference counting to CompletionData

Signed-off-by: Sebastien Ponce <sebastien.ponce@cern.ch>
Added missing semaphore in libradosstriper AIO tests leading to potential memory corruption and thus test failures

Signed-off-by: Sebastien Ponce <sebastien.ponce@cern.ch>