New scenario test case for TLD + re-factoring

1) Moving "test_create_zone_for_not_existing_tld" from API
   to scenario: "test_create_zone_using_not_existing_tld"
   Create a Zone using not existing TLD is supposed to FAIL
2) New test case: "test_create_zone_using_existing_tld"
   Create a Zone using existing TLD is supposed to PASS
3) Using indexes instead of underscores variables
4) Adding "tld_suffix" parameter into configuration (default is: 'com')
   to avoid (Non existing TLD) issues. All tests will be using
   the same(common) TLD suffix.

Change-Id: Ie9fca2598a3eab66f9cbd718e52e575744def160
6 files changed