Ignore comments deleted when deleting parent post

[fjarrett]

We noticed a very large number of records coming flooding in from a certain site all relating to comments being deleted, but they weren't system actions, it was being done by a real user.

It turns out that when you permanently delete a post it also permanently deletes the comments on that post and attributes you as the one who deleted them.

This means that deleting 1 post that has 100,000 comments on it would result in 100,001 Stream records created. 😸

We need to ignore comment deletion in these cases and perhaps find a way to say how many comments were deleted inside 1 record. Such as: 2,000 comments deleted from "Hello, world"

/cc @lukecarbis @shadyvb