act_as_paranoid integrity breakage for deployment

[martinpovolny]

due to the use of acts_as_paranoid in Deployments the the FK constraints cannot not be there (the referenced entities do not use acts_as_paranoid)

example problem: (soft) deleting a deployment and then deleting a pool could lead to a link to an non-existent pool from a deployment etc.

funny point is no test fails :-(

[martinpovolny]

the solution will be along the idea of

• expanding the "soft-delete zone" in conductor ER model
• NULLifying the relations that cross the soft-delete border in the model
• adding FKs to really enforce the relation