improve tests for Process.__str__
improve tests for Process.__str__

jamesblunt/psutil,0-wiz-0/psutil,Q-Leap-Networks/psutil,jorik041/psutil,cloudbase/psutil,mrjefftang/psutil,mrjefftang/psutil,msarahan/psutil,qbit/psutil,qbit/psutil,qbit/psutil,cloudbase/psutil,0-wiz-0/psutil,cloudbase/psutil,giampaolo/psutil,jamesblunt/psutil,giampaolo/psutil,mrjefftang/psutil,jorik041/psutil,Q-Leap-Networks/psutil,msarahan/psutil,jorik041/psutil,jamesblunt/psutil,msarahan/psutil