CONN-1148: Added X12 Schema file to Schemas and updated Pom file to incl...

...ude new schema file.
I believe this type and the one above for unsecured only need the x12:COREEnvelopeRealTimeResponse. Not the assertion/nhintargets. In fact, since this is the case can we just use that type as the response? No need to wrap it in a RespondingGateway_ type right?