Handle delete_* capabilities

[marcochiesi]

The current version of the plugin only handles edit_* capabilities but not delete_*. This brings to odd situations where a user cannot edit a post, but he can delete it, which is paradoxical.
Example: if you create a page and set it as accessible by Admin only, Editors will be able to delete it while not being able to edit. Since this is a very typical use case, I think it should be addressed somehow. You should add the proper delete capabilities when you check for permissions.

A further step would be to have separate settings for editing and deleting items. Example: an Editor should be able to edit a particular page, but not the delete it.

[marcochiesi]

What do you think about adding unit testing for delete_* capabilities too?

[tlovett1]

+1000 on unit testing.