Renamed location to storage_box in seed_stocks.
Wrapping mass upload in a single database transaction
Added field homozygous to seed_stocks
Merging mpipz's master branch
Added new role 'guest'

Permissions changed in the following manner:
 - Administrators can do everything
 - Curators can delete all models except users and roles
 - Scientists can create and update all models except users and roles
 - Guests can read everything
Added permission to view history to role 'guest'