Added needed to DC visualization fields.
Merge pull request #528 from andrzej-jankowski/rack-params

Added needed to DC visualization fields.
Accessory model changes:added better __unicode__ + removed unique constraint
Merge pull request #529 from xliiv/accessories-improvments

Accessory model improvements
changed accessory model schema to many-to-many
Merge pull request #531 from xliiv/m2m-accessories

accessory as many-to-many