Ticket 23600

Make django.core.files.storage.default_storage take account of overriding of the following settings:

MEDIA_URL
FILE_UPLOAD_PERMISSIONS
FILE_UPLOAD_DIRECTORY_PERMISSIONS

`assertEquals` is deprecated and should be replaced by `assertEqual`.
In a more personal-taste spirit, is it really useful to make 4 separate tests instead of consolidating them into one? The fact that the last 3 are identically named is an error, for sure.