Updated an inconsistent test within the StructuralSetSpec.
Added specialised Delete method for GenericParent resources. This will delete the child FileAssets before deleting the parent.
Added Abilities for updating set permissions
This commit added Delete ability to resource edit. Note that Delete can only be done in certain cicurmstances depending on the logic within ability.rb. File changes include:-
 - Destroy actions added to controllers
 - Form Action partial created for use within all resources (gives save and delete buttons)
 - specs for controller additions
Removed duplicate controllers