Allow for extra paths to be added during r.js building.

@@ -537,9 +537,9 @@ module.exports = function (grunt) {
 
                         dir: 'dist/build/scripts',
                         locale: 'en-us',
-                        paths: {
+                        paths: _.extend({
                             'defaults': 'empty:',
-                        },
+                        }, mpConfig.requirePaths),
                         modules: mpConfig.modules,
                     },
                 }