News etc. Entry soft deletion (#1882)

[daveoconnor]

This relates to ticket #1882.

Entry items are blog posts, news, etc. Added Entry deleted flagging and ability for moderators to view marked items.

Testing:

1. Publishing requirements should function the same.
2. Users who receive a moderation email can now view a previously "deleted" Entry item using the link in the email, with a red block at the top indicating who marked it as deleted (see image below).
3. Users who authored an entry item should still be able to see the deleted item, with a red block at the top indicating who marked it as deleted.
4. Entry items that have been deleted should not be visible to logged in users who are without user or group change_entry permissions or superuser status.
5. Entry items that have been deleted should not be visible to users that are not logged in.
6. Entry items that have been deleted should not show up in the listings.

Note: this image shows "None" because the user is a local superuser with no name assigned. It should contain the user's name according to their profile in use. This is the view for moderators and the author. No one else should see this.