Merge pull request #20 from schinckel/master

Added support for tox.
Fix correct future import in newrelic module
Bumped version to 0.12.5.1
Add better support for Field.default
Add Field.null
Add null testing in ModelSerialiser
Updated changelog
Add support for validation handling in serialiser inflate
Updated changelog
Remove stray experiment
Handle value inflating more precisely
Change from auto-importing "serialiser" to "publishers"
Fix test code
Updated changelog
Avoid issues with current cache API limitations
Merge branch 'master' of github.com:funkybob/django-nap
Only set default if the model field has one
Don't deflate NoDefault
Bumped version to 0.13.0
Fixed braino
Bumped version to 0.13.1