Add Snackbar for Auto Update

When the feed is auto updated, we should display a material snackbar that alerts the user that their data has changed. Follow the material design documenation for implementation details on the snackbar.

snackbar:

• should be open for 3 seconds
• user should be able to dismiss the snackbar before the full 3 seconds

The message should alert the user if:

• the feed is currently loading
• the feed loaded successfully
• the feed failed to load