replaced my debug lib with standard one

lib/streams/RollingFileStream.js

@@ -1,6 +1,6 @@
 "use strict";
 var BaseRollingFileStream = require('./BaseRollingFileStream')
-, debug = require('../debug')('RollingFileStream')
+, debug = require('debug')('log4js:RollingFileStream')
 , util = require('util')
 , path = require('path')
 , fs = require('fs')
@@ -53,13 +53,13 @@ RollingFileStream.prototype.roll = function(filename, callback) {
 
   function increaseFileIndex (fileToRename, cb) {
     var idx = index(fileToRename);
-    debug('Index of ' + fileToRename + ' is ' + idx);
+    debug('Index of ', fileToRename, ' is ', idx);
     if (idx < that.backups) {
       //on windows, you can get a EEXIST error if you rename a file to an existing file
       //so, we'll try to delete the file we're renaming to first
       fs.unlink(filename + '.' + (idx+1), function (err) {
         //ignore err: if we could not delete, it's most likely that it doesn't exist
-        debug('Renaming ' + fileToRename + ' -> ' + filename + '.' + (idx+1));
+        debug('Renaming ', fileToRename, ' -> ', filename, '.', (idx+1));
         fs.rename(path.join(path.dirname(filename), fileToRename), filename + '.' + (idx + 1), cb);
       });
     } else {