revert to node6 on travis and remove extra comma in gulp

Author: wti806

.travis.yml

@@ -1,6 +1,6 @@
 language: node_js
 node_js:
-  - '8'
+  - '6'
 install: npm install
 script: npm test -- --saucelabs
 before_install:

gulpfile.js

@@ -172,7 +172,7 @@ function repeatTaskForAllLocales(taskName, dependencies, operation) {
     const localeDependencies = dependencies.map(replaceTokens);
     gulp.task(localeTaskName, gulp.series(
         gulp.parallel.apply(null, localeDependencies),
-        () => operation(locale),
+        () => operation(locale)
     ));
     return localeTaskName;
   });