Fix windows copy command

Author: Juho Hovila

mbed_flasher/flashers/FlasherMbed.py

@@ -213,7 +213,7 @@ def copy_file(self, source, destination):
                              return_code=EXIT_CODE_OS_ERROR)
 
     def _copy_file_windows(self, source, destination):
-        command = "copy {} {}".format(os.path.abspath(source), destination)
+        command = "copy \"{}\" \"{}\"".format(os.path.abspath(source), destination)
         self.logger.debug("Copying with command: {}".format(command))
         subprocess.check_call(command)