fix error when run unittest case

fix error when run unittest case

when run tox -epy27, there are errors in function of test_relationship
for key in relation.keys():
    rel_tpl = relation.get(key).get_relationship_template()
    if rel_tpl:
        self.assertEqual(
            rel_tpl[0].type, "tosca.relationships.ConnectsTo")
rel_tpl is a list so real_tpl[0].type can be other value, not only
tosca.relationships.ConnectsTo.

JIRA: PARSER:61

Change-Id: Ibdc7307888f5281ac0bd806088483f8c46416968
Signed-off-by: shangxdy <shang.xiaodong@zte.com.cn>