Issue with adding a comment on demo board where user does not have an avatar

[mpmmasterpeace]

Issue

Submitting a comment utilizes the user's avatar_url. This does not work on demo mode where the user does not have an avatar.

Solution

Safely create an avatar url checking for existence. Use '' if it does not exist.
Also, for display, use an icon if user has no avatar.

[Alchemist]

oh weird!