Fix "username" property on Windows 7 which, for certain processes, returns "None\None", in which case AccessDenied gets raised instead. This matches procexp behavior which fills such process with a "<access denied>" string.
Fix "username" property on Windows 7 which, for certain processes, returns "None\None", in which case AccessDenied gets raised instead. This matches procexp behavior which fills such process with a "<access denied>" string.

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