improve raven setup comment

Author: takempf

lib/server.js

@@ -102,7 +102,8 @@ var SolidusServer = function( options ){
 	}));
 	// catch-all middleware at the end of the stack for 404 handling
 	router.use( router.router );
-	// log express errors to sentry if defined
+	// log express errors to sentry
+	// log uncaught exceptions to sentry and exit
 	if( SENTRY_DSN ){
 		router.use( raven.middleware.express( SENTRY_DSN ) );
 		var raven_client = solidus_server.raven_client = new raven.Client( SENTRY_DSN );