Docs, no ID and callbacks

• Shortened bower description to remove bower warning on install (thanks @jcubic)
• Thanks to @Lorelei for the pull request to pass the event back in the callback function
• Thanks to @CosticaPuntaru for the improvement to now allow the directive to no longer need an id on the element for this to work
• Added basic ngdocs documentation
• Removed the addition of the element id to the classes array as now it no longer needs to be checked