Discussion: Fake user comment is displayed even if the comment couldn't be posted

When a user adds a comment in a discussion, the app immediately adds it to the array of currently shown comments so that the users comment is displayed immediatlely. The reason for this is that there is a fairly long cache otherwise.

However, if the comment fails to be posted (Eg because you rate limit comments to 1 per minute), we still display this comment in the list on comments as if it had been posted.

We should check to see if the post has been successful before displaying it in the list of comments.