Timezone aware

[duduklein]

I made the timezone aware issue compatible with django 1.3

Basically, I try to import django.utils.timezone and when it fails, it falls back to datetime.datetime

I had to import timedelta directly when needed, i.e., from datetime import timedelta in order to use datetime as before.

I also made the use of dateutil optional. It if's not present, it will fall back to strptime. What I don't really like about this, is that the timezone is hardcoded (+0000). dateutil will detect the correct timezone.

I would like to add some tests to make sure that all the importerrors fall back to the original state, but I could not find a way to impose the ImportError (like using mock library). Any ideas on how to do this?

[tschellenbach]

Yeay raising import errors is quite hard. You can replace the builtin import function, but that isn't so nice.

If the import is done at the function and not the module level it is easy to raise using the side_effect attribute of the Mock.

The code isn't pep8 at the moment.
$ pep8 --exclude=migrations --ignore=E501,E225 django_facebook open_facebook
django_facebook/utils.py:2:56: W291 trailing whitespace
django_facebook/utils.py:458:1: E302 expected 2 blank lines, found 1
django_facebook/utils.py:459:59: W292 no newline at end of file

Other than that looks good though, merging :)