Returns a properly formatted ghost file name.

        :returns: formatted ghost_file name (string)

def formatted_ghost_file(self):
        """
        Returns a properly formatted ghost file name.

        :returns: formatted ghost_file name (string)
        """

        # replace specials characters in 'drive:\filename' in Linux and Dynamips in MS Windows or viceversa.
        ghost_file = "{}-{}.ghost".format(os.path.basename(self._image), self._ram)
        ghost_file = ghost_file.replace('\\', '-').replace('/', '-').replace(':', '-')
        return ghost_file