fetchNewNotifications abstract method

Fetch new notifications. While fetchNextPage() is used to fetch older notifications than the ones currently loaded, this method checks for new notifications. For example, this is the method you would call on initial load, or on a "pull to refresh". The previously loaded notifications will be cleared to ensure consistency. Otherwise, a gap could be created between new notifications and your current set. Upon calling this method, please clear your cache and fill it with this method's results and ask again for more pages if you need.