let dummy callback take any number of arguments
Let success/fail callbacks know whether the transaction status has changed, to avoid sending multiple notifications etc
Remove get_absolute_url stub
Merge branch 'master' of https://github.com/gregplaysguitar/django-dps
Paranoid check - let's be extra careful when setting Transaction status in an unauthenticated GET request
trimmed a couple of line lengths
Merge pull request #4 from gregplaysguitar/master

Atomic status updates, and callback protocol updates to match. (Plus extra sanity checks.)