'RenameField should optimize into AddField'

def test_add_field_rename_field(self):

    self.assertOptimizesTo([migrations.AddField('Foo', 'name', models.CharField(max_length=255)), migrations.RenameField('Foo', 'name', 'title')], [migrations.AddField('Foo', 'title', models.CharField(max_length=255))])
