Hidden stories still notify about comments

[pushcx]

The replying_comments view needs to be updated to ignore replies if the user has hidden the story.

Comment#deliver_mention_notifications needs to ignore replies if the receiver has hidden the story.

Comment#deliver_reply_notifications needs to ignore replies if the receiver has hidden the story. Maybe this is best implemented in users_following_thread but I haven't audited all functions that call it.

[Jaskaran2]

Hi is this issue still up for grabs??

[pushcx]

Yup. Issues tagged 'good first issue' are pretty much always ready to be picked up! We don't assign issues and I try to only rarely (and explicitly) claim issues myself.