[mid] add Yuuna Ego, modify Aya Shibata
[gpupdate.rb] check if correctly get member info from G+

  This is workarround for following exception:
  gpupdate.rb:135:in `block in <main>': undefined method `display_name' for nil:NilClass (NoMethodError)
[lib/dbmodels.rb] check if download image is GURU.PNG

  If the image is GURU.PNG, now set status to 6 (IMAGE_STATE_GURU).
[gpupdate.rb] now, first of all, update image_url from G+ when status = IMAGE_STATE_GURU