Unauthenticated users may see a "forever loading" failure state

[mike-north]

What's the problem?

Some users, upon attempting to load ember-twiddle (either viewing an existing twiddle, or creating a new twiddle) see nothing except a big loading spinner that never goes away

Why does this happen

Unauthenticated users are rate-limited by GitHub, and there does not appear to be appropriate error handling in place to surface this information in the UI

Who This Affects

Users who end up in a GitHub API rate limited state (e.g., they're on a corporate network with many other users, and have not logged into twiddle with their github account).

How this problem can be significantly mitigated

We could improve the mode of failure so that it tells the user what's going on in this failure state, and presents them with a "next best action" is (e.g., login to github so they're no longer rate limited by IP address).

Related Tickets

#375