Rename project and rename its root path accordingly.

def rename(self, new_name):
        """Rename project and rename its root path accordingly."""
        old_name = self.name
        self.name = new_name
        pypath = self.relative_pythonpath  # ??
        self.root_path = self.root_path[:-len(old_name)]+new_name
        self.relative_pythonpath = pypath  # ??
        self.save()