use UTF-8 for string representation

source/filesystem/fs_utility.cpp

@@ -50,6 +50,7 @@ namespace filesystem
 	typedef nana::string string_t;
 	const nana::char_t* splstr = L"/\\";
 #endif
+
 	//class path
 		path::path(){}
 
@@ -122,6 +123,7 @@ namespace filesystem
 		}
 	//end class path
 
+
 	namespace detail
 	{
 		//rm_dir_recursive