How would one obtain the URL to a image blob stored on GAE's
datastore? A lot of the threads I've looked at were all for generating
an download output for views, but I need this for the Controller since
I'm returning this as a JSON element.
For example, the auth_user table has a field 'avatar' and another blob
field 'avatar_blob'. Ideally I can simply return a JSON like:
{ "avatar": "http://<domain>/<app>/avatars/username_avatar.gif" }
Where username_avatar.gif would map to the stored blob image for that
user's avatar.
