+ issue #163: added foreign keys to the database model.
+ added description picture for the database model
+ changed relation between Contact Person and Crawl Permission classes.
+ issue #163: added foreign key constraint between User and Organsation.
+ data import update for fk.
+ issue #136: implemented association between Organisation and Target.
+ issue #136: implemented associations for Permission/Role, Instance/Organisation and Target/CrawlPermission.
+ fix for Instances import in DataImport.
+ issue #136: update target to crawl permission association by target editing due to target revisions complexity.
+ issue #163: implemented association Collection/Target.
+ issue #136: implemented association Target to Subject.
+ issue #136: implemented association Tag to Target and Flag to Target.
+ issue #136: implemented association between Target and License.
+ issue #163: implemented association Instance to Subject.
+ issue #136: implemented association Instance to Collection.
+ issue #136: implemented associations between Instance and Tag, Flag, Collection.
+ issue #136: implemented ManyToMany association for Subject and Target.
+ issue #136: added many to many association for Instance and Subject.
+ fix for collection presentation in Instance edit page.
+ issue #136: implemented many to many associations for Collection/License and Target/Instance