Fix order of plugins assets copy

lib/output/website/copyPluginAssets.js

@@ -13,7 +13,11 @@ var fs = require('../../utils/fs');
     @return {Promise}
 */
 function copyPluginAssets(output) {
-    var plugins = output.getPlugins();
+    var plugins = output.getPlugins()
+
+        // We reverse the order of plugins to copy
+        // so that first plugins can replace assets from other plugins.
+        .reverse();
 
     return Promise.forEach(plugins, function(plugin) {
         return copyAssets(output, plugin)