feat(rxStatusSvc): Wrapper for rxNotify.

This provides a wrapper around `rxNotify` in order to make the repetitive usage of `{ type: 'success' }` type options less necessary.

It only works with singular messages today; the feature provided by `rxPromiseNotifications` is not being wrapped.

Thanks to @chriscantu for the initial version of the awesome service provided for vcenter-ui.
Thanks to @parlarjb for updating it with awesome features that makes the service even more usable.
If this PR gets merged, I will burn this repo to the ground.

![DoesNotLGTM](http://static.fjcdn.com/gifs/merica+in+one+gif_5487b0_4785103.gif)