Fix processign of mpConfig.jshint.main, it wasn't finding files at the

top-level of src/scripts.

@@ -254,7 +254,7 @@ module.exports = function (grunt) {
                 ],
                 main: {
                     options: _.extend({}, mpConfig[name].browserOptions, browserOptions),
-                    files: _.map(_.concat([], mpConfig.mainDirs), function (value) {
+                    files: _.map(_.concat([''], mpConfig.mainDirs), function (value) {
                         return {
                             src: mpConfig.base + '/scripts/' + value + '/{,**/}*.js',
                         };