Fixes #4870, bz1113398 - Added missing foreign key associations

Also contains updates to association tests if foreign key constraints
are not defined in 'belongs_to' associations for all Katello models.
Fixes #6409, bz 1113684 - Bulk Product destroy dynflowed.

Dynflowed the bulk product delete code.
Merge pull request #4355 from parthaa/bulk-product-destroy

Fixes #6409, bz 1113684 - Bulk Product destroy dynflowed.
Merge pull request #4353 from parthaa/fk

Fixes #4870, bz1113398 - Added missing foreign key associations