Implement Ability to Comment on Reports

[jordan-wright]

It should be possible for analysts to leave comments on reports. I'd like this to look similar to how Github comments appear from within issues.

This would let analysts leave notes for one another or leave a closing note after a report is triaged.

Reports should be able to store zero or more comments and the comments should be visible from within the main report view.

[kiwiz]

What about comments from users (during the initial report)? I've got a PR I can submit if there's interest. :]

[jordan-wright]

I think that's a great idea! Giving the user the ability to comment on a report before it's sent upstream would be super beneficial. I've opened up #21 to track this if you'd like to send up a pull request.

Thanks for the suggestion!