Added has_avatar tag to profiles and updated templates

has_avatar will return the URL of a custom avatar. If there is the avatar hasn't been set, it will return no image.

I also updated templates that use {% avatar %} to use {% has_avatar %}

Signed-off-by: bpotterschipul <bpotter@schipul.com>
Restored "avatar" instead of "has_avatar"

Signed-off-by: bpotterschipul <bpotter@schipul.com>