updated nodemon config to auto-reload aggregated.js/css

See related discussion here:
https://github.com/linnovate/mean/issues/529
- the purpose of this change to enable changes made to package css/js
files to be reflected in the browser after live reload
- since those files are packaged in the aggregated.js/css it requires a
server restart
- without this change, only the grunt ‘watch’ task is activated on a
change to /packages/*.js or *.css