Revert "Revert "Allow NfsPrimaryStorage.xml to be overwritten""
Revert "Revert "Allow NfsPrimaryStorage.xml to be overwritten""

This reverts commit a0be3cca35f4be88b8bc87d61dad5c23b689e073.

hhjuliet/zstack,zstackio/zstack,MaJin1996/zstack,camilesing/zstack,AlanJager/zstack,MatheMatrix/zstack,HeathHose/zstack,AlanJinTS/zstack,AlanJinTS/zstack,zstackio/zstack,zxwing/zstack-1,mingjian2049/zstack,zsyzsyhao/zstack,Alvin-Lau/zstack,mingjian2049/zstack,AlanJager/zstack,zxwing/zstack-1,MatheMatrix/zstack,camilesing/zstack,camilesing/zstack,liningone/zstack,HeathHose/zstack,mingjian2049/zstack,liningone/zstack,liningone/zstack,zsyzsyhao/zstack,zstackorg/zstack,MaJin1996/zstack,zstackorg/zstack,MatheMatrix/zstack,zstackio/zstack,AlanJinTS/zstack,Alvin-Lau/zstack,zxwing/zstack-1,winger007/zstack,Alvin-Lau/zstack,AlanJager/zstack,winger007/zstack,WangXijue/zstack,HeathHose/zstack,WangXijue/zstack,WangXijue/zstack,hhjuliet/zstack