Replace ok with circle for boolean icon

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Enable identicon for gravatar by default

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Change gravatar tests to identicon

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>