fix(test): fix task finishing before test

Author: klarkc

template/gulp-tasks/test.js

@@ -5,7 +5,7 @@ import path from 'path';
 import {dirs} from './config.js';
 
 gulp.task('test:server', () => {
-  gulp.src(path.resolve(dirs.testServer, '**/*.test.js'))
+  return gulp.src(path.resolve(dirs.testServer, '**/*.test.js'))
   .pipe(mocha({
     compilers: 'js:babel-core/register',
     require: path.resolve(dirs.test, 'mocha.conf.js'),