Adds negative unittests to test_domains.py and test_records.py

This submission adds two negative tests under
"designate/tests/test_api/test_v1/test_domains.py" script.
Following are the negative tests -
1. test_update_domain_negative_ttl
2. test_create_domain_invalid_ttl

Also,adds one negative test under
"designate/tests/test_api/test_v1/test_records.py" script.
Negative test:
1)test_update_record_invalid_ttl

Change-Id: I0a09661823e62740c65aa1893c757e4c1353bdbe
Merge "Adds negative unittests to test_domains.py and test_records.py"