Remove unnecessary return

Return value of `mergeMiddlewares` and `setUserRewriteRules` is not
used.

Author: 38elements

lib/async.js

@@ -181,7 +181,7 @@ module.exports = {
      */
     mergeMiddlewares: function (bs, done) {
 
-        return done(null, {
+        done(null, {
             options: {
                 middleware: bs.pluginManager.hook(
                     "server:middleware",
@@ -196,11 +196,10 @@ module.exports = {
      * be live updated inside resp-modifier/foxy
      * @param bs
      * @param done
-     * @returns {*}
      */
     setUserRewriteRules: function (bs, done) {
         var userRules = bs.options.get("rewriteRules");
-        return done(null, {
+        done(null, {
             instance: {
                 rewriteRules: userRules ? userRules.toJS() : []
             }