Using DatabaseStorage in Python3

[ryanmcfall]

First of all, if this code is dead, just let me know. It hasn't been touched in quite a while.

I tried to use the code as is, and ran into a problem simply executing:

from database_storage import DatabaseStorage

I believe this is due to some problems with changes between Python 2 and Python 3. I was able to make a local copy of database_storage.py and get it to work by modifying a couple of imports:

from io import StringIO
from urllib.parse import urljoin

and then changing the call to urljoin within the url method to be just

result = urljoin(self.base_url, name).replace('\\', '/')

I also had to do the following to make the Django migration framework happy:

from django.utils.deconstruct import deconstructible

@deconstructible
class DatabaseStorage(Storage):

Without this makemigrations complains that the ImageField that uses DatabaseStorage isn't serializable.

Can you verify these changes are correct, and if so, integrate them so I can reinstall the module using pip?

I can submit a pull request if you'd prefer.