Make token a field on Subscriber model, make django 1.5 changes, etc

Change whitespace from tabs to spaces!

forms.py:
- fix my error calling current_site before declaration

models.py:
- make token a field on Subscriber model
- change token generation to make a bigger base36 number

urls.py:
- change url conf import from depreciated django.conf.urls.default
- remove unused import

templates:
- change url template tag to use django 1.5 syntax (i.e. added quotation marks)

And probably some other changes I've forgotten to include here.