Add sanity check to validate all suites against suite schema. Make sure optional test suites don't skip the sanity checks.
Add sanity check to validate all suites against suite schema.
Make sure optional test suites don't skip the sanity checks.

moander/JSON-Schema-Test-Suite,WHenderson/ex-json-schema,json-schema/JSON-Schema-Test-Suite,epoberezkin/JSON-Schema-Test-Suite,atomiqio/json-schema-test-suite,json-schema-org/JSON-Schema-Test-Suite,epoberezkin/JSON-Schema-Test-Suite,mafintosh/JSON-Schema-Test-Suite,neomadara/JSON-Schema-Test-Suite,Relequestual/JSON-Schema-Test-Suite,WHenderson/ex-json-schema,atomiqio/json-schema-test-suite