Refactored and simplified code

xroot_plugins/CMakeLists.txt

xroot_plugins/ParsedArchiveCmdLine.cpp

xroot_plugins/ParsedArchiveCmdLine.hpp

xroot_plugins/ParsedChangeStorageClassCmdLine.cpp

xroot_plugins/ParsedChangeStorageClassCmdLine.hpp

xroot_plugins/ParsedCreateStorageClassCmdLine.cpp

xroot_plugins/ParsedCreateStorageClassCmdLine.hpp

xroot_plugins/ParsedDeleteStorageClassCmdLine.cpp

xroot_plugins/ParsedDeleteStorageClassCmdLine.hpp

xroot_plugins/ParsedListStorageClassCmdLine.cpp

xroot_plugins/ParsedListStorageClassCmdLine.hpp

xroot_plugins/ParsedRequest.cpp

xroot_plugins/ParsedRequest.hpp

xroot_plugins/ParsedRmdirCmdLine.cpp

xroot_plugins/ParsedRmdirCmdLine.hpp

xroot_plugins/XrdProFilesystem.cpp

xroot_plugins/XrdProFilesystem.hpp