Reports spec as valid when other validators do not #89

I have a spec which this project reports as valid where other validators, such as speccy, do not.

What I've found is that the spec we were using had duplicate entries for a get response of 200. This causes the other validators to throw an error.

I modified the test_parameter_default_value_wrong_type_swagger testcase in test_validators.py to add a duplicate 200 response with a different description and the error was not reported.