Get TITLE and DESCRIPTION from siteconfig directly

Instead of changing django.conf.settings at runtime which we should not
be doing:
    https://docs.djangoproject.com/en/dev/topics/settings/#altering-settings-at-runtime

Fixes bug 3150.
Accept `sfields` to be a comma-separated string of fields

This aligns with the query parameters accepted in the editor and allows
using both comma-separated and multiple parameter forms.

Fixes evernote#46.
Identify 404 errors as such