add block_type to the south introspection rules

Conflicts:
	src/django_fields/fields.py
add block_type to the south introspection rules

Conflicts:
	src/django_fields/fields.py
fix multiple object failure, plus a test to prove it.
fix multiple object failure, plus a test to prove it.
Merge branch 'multisave' of github.com:defrex/django-fields into multisave

Conflicts:
	src/django_fields/tests.py
Merge branch 'multisave'

Conflicts:
	src/django_fields/tests.py
Merge branch 'south'