Bugfix: use fsm_field instead of 'state'

When enumerating possible transitions, obj.state was always used, disregarding the fsm_field class attribute.
Merge pull request #7 from knaperek/patch-1

Bugfix: use fsm_field instead of 'state'
Update Django version in requirements.txt

There's no need to fix Django to a specific minor version, they're all compatible and do not introduce any API changes, only bugfixes.
Merge pull request #8 from knaperek/patch-2

Update Django version in requirements.txt