Better handling for browsers with cookies disabled

[cmcfadden]

The app will fail in all sorts of ways if cookies are disabled. Shibboleth will fail too, so this will mostly impact students using the Canvas app on a mobile device, popping into the browser - they wouldn't have been able to use canvas otherwise.

We can potentially detect that cookies aren't being retained and throw up a message but it's a little tricky with httponly cookies, etc.

[cmcfadden]

Also, do some research on the "privacy centric" browsers that might be on the app stores that just block all cookies. Think about trapping for them?