DNN-4451 - update codemirror to 4.7 release

updates codemirror to the latest release which also fixes an issue when cdf is enabled with minification options turned on. i'm not sure the previous version we were using. release notes from codemirror can be found here. http://codemirror.net/doc/releases.html

if you enable cdf and minify js/css, navigate to any page which uses codemirror (site settings, sql module, config mgr, etc) and it will not function correct (js errors). after upgrading to 4.7, increment the cdf version, functionality is restored.