Update version to beta-4

Author: dpvc

unpacked/MathJax.js

@@ -47,7 +47,7 @@ if (window.MathJax) {window.MathJax = {AuthorConfig: window.MathJax}}
 
 MathJax.version = "2.5.0-beta";
 MathJax.fileversion = "2.5.0-beta";
-MathJax.cdnVersion = "2.5.0-beta-3";  // specifies a revision to break caching
+MathJax.cdnVersion = "2.5.0-beta-4";  // specifies a revision to break caching
 MathJax.cdnFileVersions = {};       // can be used to specify revisions for individual files
 
 /**********************************************************/