feat(rxStatus): attr edit for success/error banners; Resolves #420

Addresses issue #420, adding timeout and repeat=false attributes to success banners and a repeat=false attribute to error attributes. Once this is merged in, I will need to delete `status.js` and `status.spec.js` from encore-cloud-ui and remove the import of `status.js` from encore-cloud-ui's `index.html`.
Can you add a comment here about the reasoning behind this? Basically that we don't want to repeat 'success' or 'error' messages.