Adds HTML support, ability to hide close button, & configuration for hide timer.

As you can probably tell by my commits, I'm new to this whole contributing thing, but I think other people could benefit from the enhancements here.

This also includes https://github.com/dmaslov/ng-notifications-bar from @dmaslov who added a notificationsConfigProvider where you can globally set the timeout speed for notifications. 

In addition, I added HTML support in message (if you use user generated strings in messages from users in your app, be careful!) and the ability to hide the close button (incase you want to be annoying). Hopefully people can use these features.