Add grunt-notify to watch tasks

[maff]

Adds a system notification via grunt-notify when starting/completing LESS or JS building.

[QWp6t]

This could probably be refactored. I'm wondering if we could create a rootsTasks(...) function that will dynamically compile that notify object (to something like rootsNotifications = {}) based on parameters passed to it, and then return the same array it was sent..

Then each watch task would be something like

tasks: rootsTasks(['less:dev', 'autoprefixer:dev'])

And notify could be something like

notify: rootsNotifications

Seems like that would be good for staying DRY. On the other hand, I have no idea how well this notify thing works or if we really even need it. That's not to mention that we're moving away from Grunt, so perhaps this should be revisited once we make the switch over to Gulp.

[retlehs]

we're moving away from Grunt, so perhaps this should be revisited once we make the switch over to Gulp.

^^

[retlehs]

ref #1138