Added 'destroy' method that is called on deleted instances

Added ability to modify/remove data from structures (like Heat
templates) via jsonpatch and thus added ability to clean up Heat
resources that was obtained by deleted instances

Closes bug: #1296624

Change-Id: I4db226a5ab00ff363f8b5d44a5d690df942622e8
Merge "Added 'destroy' method that is called on deleted instances"