fix prepare-test-files task

Author: Vladimir Demidov

Gruntfile.js

@@ -182,12 +182,12 @@ module.exports = function (grunt) {
 grunt.loadTasks('./custom-tasks/');
 
 // "npm build" runs these tasks
-// big.jpg added to git
-/*grunt.registerTask('prepare-test-files', function (){
-if (!grunt.file.exists('tests/files/big.jpg')) {
+grunt.registerTask('prepare-test-files', function (){
+// big.jpg added to git
+/*if (!grunt.file.exists('tests/files/big.jpg')) {
 grunt.task.run('curl');
-}
-});*/
+}*/
+});
 
 grunt.registerTask('express', 'Start a custom web server.', function() {
 var done = this.async();