[#69597566] Add ui validation for blank comment

Add a listener to add a disabled class to the add comment button when
there are no characters in the comment to be submitted.
Disable add comment button on render.
[#69597566] Method on event for root comments
[#69597566] Only logged in users can comments

Make comments module aware of the user that is logged in.
Use the username to populate the user name in the comment.
Add spec for comment created with username.
Hide new comment box when user is not logged in.
[#69597566] Event reference on all comments