adding example pstree.py with some fixes
adding example pstree.py with some fixes

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