MANIFEST.in: Add docs and tests (#362)
MANIFEST.in: Add docs and tests (#362)

Also include all language translations in sdist.

Fixes https://github.com/jazzband/django-model-utils/issues/361 and closes https://github.com/jazzband/django-model-utils/issues/356
carljm/django-model-utils,carljm/django-model-utils