Fix for de-serialization.
Using vanilla django-money, when one did the following:

./manage.py dumpdata

the values were saved properly, i.e:

{
  'amount': '12',
  'amount_currency': 'USD',
}

however, after the de-serialization:

./manage.py loaddata [fixtures]

the currencies were omitted.

i have no idea (yet) how to write a test that proves that.. :/
added reversion tests for testing serialization and deserialization
Merge branch 'master' of git://github.com/toudi/django-money into toudi-master

Conflicts:
	djmoney/serializers.py