Merge pull request #40 from septs/master

lazy require fs

lib/po.js

@@ -1,5 +1,3 @@
-var fs = require('fs');
-
 function trim(string) {
     return string.replace(/^\s+|\s+$/g, '');
 }
@@ -13,7 +11,7 @@ var PO = function () {
 };
 
 PO.prototype.save = function (filename, callback) {
-    fs.writeFile(filename, this.toString(), callback);
+    require('fs').writeFile(filename, this.toString(), callback);
 };
 
 PO.prototype.toString = function () {
@@ -65,7 +63,7 @@ PO.prototype.toString = function () {
 };
 
 PO.load = function (filename, callback) {
-    fs.readFile(filename, 'utf-8', function (err, data) {
+    require('fs').readFile(filename, 'utf-8', function (err, data) {
         if (err) {
             return callback(err);
         }