make ?cacheBust QP a flag, phetsims/chipper#767

Author: zepumph

js/equality-explorer-config.js

@@ -45,6 +45,6 @@ require.config( {
     VEGAS: '../../vegas/js'
   },
 
-  // optional cache bust to make browser refresh load all included scripts, can be disabled with ?cacheBust=false
+  // optional cache bust to make browser refresh load all included scripts, can be enabled with ?cacheBust
   urlArgs: phet.chipper.getCacheBustArgs()
 } );