Missing appName in config server log message

Continuation from SERVER-25903. This log message is from a config server running _configsvrAddShard and doesn't include the app name. But all _configsvrAddShard requests come from a mongos running 'addShard' and all 'addShard' requests must be manually run, in the case of our jstests, all addShard requests should come from the shell and thus should have MongoDB Shell as the appName.