Prohibit setting fcpsschools.net as an email

[theo-o]

Blocks users from setting an fcpsschools.net address via preferences.

Fixes #599

[coveralls]

Coverage increased (+0.05%) to 49.685% when pulling 7301540 on email-validation into 46cc7ba on dev.

[ghost]

One nitpick, and I would recommend adding this to intranet/apps/preferences/views.py:

@ -52,6 +52,9 @@ def save_personal_info(request, user):
     if email_formset.is_valid():
         email_formset.save()
     else:
+        for error in email_formset.errors:
+            if isinstance(error.get("address"), list):
+                errors.append(error["address"][0])
         errors.append('Could not set emails.')
     if website_formset.is_valid():
         website_formset.save()

Tested locally, it makes the ValidationError's error message ("You cannot provide an fcpsschools.net address.") appear as a notification, which makes it more obvious to the user what's going on.

[ghost]

LGTM