json_matchers should not read _every_ .json file in schema_root

[jasonkarns]

We have our schemas stored in our app directory in various locations because the schemas are not used solely for testing. Therefore, I attempted to set the schema_root to our app root. However, that caused json_matchers to start assuming any and all *.json files were json schema. Hence, it began blowing up with odd errors as most of these json files were not json schema.