Decreased the number of directories handled by the watch task

Grunt now "watches" html files only in the root directory of the app or in the "templates" directory. This should increase performance (https://github.com/gruntjs/grunt-contrib-watch/blob/3ec9cd8d7f91262ddb713a2f0968eb08067135b3/README.md#why-is-the-watch-devouring-all-my-memory)