Why are we doing this?
For contributors who have a large number of messages, we will need to be able to present a loading state as the table view is loaded at the end of each 'page' load.
- Image should rotate (spin) until the new set of notifications is loaded
- Spinner appears at the bottom of the loaded section of the table.
- Utilize the theme's 'primary action' color (eg #36C for default) for the color of the spinner