Chore: Fix no-unused-expressions

http://eslint.org/docs/rules/no-unused-expressions

bin/node-sass

@@ -166,7 +166,7 @@ function getEmitter() {
 
   emitter.on('done', function() {
     if (!options.watch && !options.directory) {
-      process.exit;
+      process.exit();
     }
   });
 
@@ -372,7 +372,7 @@ function renderDir(options, emitter) {
     }, function(successful, arr) {
       var outputDir = path.join(process.cwd(), options.output);
       emitter.emit('warn', util.format('Wrote %s CSS files to %s', arr.length, outputDir));
-      process.exit;
+      process.exit();
     });
   });
 }