Raise 404 if user attempts to access remote app with cloudcare api

Addresses http://manage.dimagi.com/default.asp?137874

If a user accessed this cloudcare endpoint with a remote app id, then `Application.get(app_id)` was raising an exception. Now we raise a 404 (instead of a 500) because remote apps are not supported by cloudcare.

I'm not adding any sort of message or redirect anywhere because I don't know how it came to be that the user hit this url (cloudcare doesn't display remote apps in it's navigation).