added powermock-classloading-xstream to attempt to fix power mock / junit rule issue on linux.
added powermock-classloading-xstream to attempt to fix power mock / junit rule issue on linux.

OpenLMIS/open-lmis,kelvinmbwilo/vims,USAID-DELIVER-PROJECT/elmis,USAID-DELIVER-PROJECT/elmis,USAID-DELIVER-PROJECT/elmis,OpenLMIS/open-lmis,kelvinmbwilo/vims,kelvinmbwilo/vims,kelvinmbwilo/vims,OpenLMIS/open-lmis,OpenLMIS/open-lmis,USAID-DELIVER-PROJECT/elmis