Multiple issues with contrib.comments moderation system

[James Bennett]

I know it's really bad form to condense multiple things into one ticket, but here goes anyway.

1. django.contrib.comments.moderation currently listens for the pre_save and post_save signals, which means the moderation system misses out on important additional information available from the custom signals defined inside the comments application.
2. moderation.py currently contains some experimental code that I never documented, never tested and never shipped in any version of comment-utils. That code should not be shipping in Django.

The attached patch deals with both of these issues, updates the relevant documentation and has passing tests.

[Jacob]

(In [10784]) Fixed #11113: fixed a couple of issues that slipped through the cracks when comment moderation was added to django.contrib.comments.

The is a potentially backwards-incompatible change for users already relying on the internals of comment moderaration. To wit:

• The moderation system now listens to the new comment_will_be_posted/comment_was_posted signals instead of pre/post_save. This means that import request-based information is available to moderation as it should be.
• Some experimental code from django.contrib.comments.moderation has been removed. It was never intended to be merged into Django, and was completely untested and likely buggy.

[Jacob]

Milestone 1.1 deleted