fixes issue that occurs when the configuration is returned as a string (instead
of being returned as a JSON object) from the /swagger_config endpoint.  Previously
this would cause an "undefined" string to appear in the URL, which would break the
swagger-ui-based documentation.  With this change in place, a return of a JSON object
should work without issues (as before) but any configuration returned as a String
should be parsed into a JSON object before it it used.