using os.tmpDir if available fixes #7

Author: raszi

lib/tmp.js

@@ -10,15 +10,17 @@
 var
   fs     = require('fs'),
   path   = require('path'),
+  os     = require('os'),
   exists = fs.exists || path.exists,
+  tmpDir = os.tmpDir || _getTMPDir,
   _c     = require('constants');
 
 /**
  * The working inner variables.
  */
 var
   // store the actual TMP directory
-  _TMP = _getTMPDir(),
+  _TMP = tmpDir(),
 
   // the random characters to choose from
   randomChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz",