Should add a way to get the entire object for deletion (local_controller)

[Shachar Snapiri]

All the object delete methods in the local controller (e.g. logical_switch_deleted) get the object ID, only to fetch it from the DB store. In most cases the code calling these methods has the object at hand, and sends the object.get_id().

There are several aspects to it:
1. We have the object at hand, but send its ID only to re-fetch it (performance issue)
2. The fetching is from the db_store, which is in-memory, so the cost is not too big (but nevertheless)
3. There are places that call these methods and only have the ID at hand, so we would have to have a way to keep the current functionality for these places in the code
Every item here has its advantages and disadvantages, a decision should be made.