ipatests: replace the test-example.com domain in tests
    
    Latest DNS patches introduced checks for the added zones.
    If a zone exists, the add fails if not forced. The domain
    test-example.com is resolvable thus causing errors in the test.
    
    Also adds missing __init__.py to the ipatests.test_cmdline package.
    
    Reviewed-By: Oleg Fayans <ofayans@redhat.com>