[gpupdate.rb] remove 11 graduates

  - riri, kasusu, shiorin, emiri, mizuki, shi-tan, shawako,
    haramina, kanako, mitsuki, and ku-min
[gpprofile.rb] add Scramble Egg
[gpupdate.rb] change option message
[gpupdate.rb] add SQL statement to debug log
[lib/dbmodels.rb] add unzip into get_file()
[lib/ske48gplus-activity.rb] check if att.full_image.url is valid URL form.

If att.full_image.url is invalid, use image_url2best(att.image.url) as image_url.
[lib/dbmodels.rb] support new album page html for scraping image URL

And if failed to scape image URL with the album page,
now status set 0 (IMAGE_STATE_NOT_CHECKED), which has
been set to 3 (IMAGE_STATE_INVALID_URL).
[mysql-backup.sh] support MySQL 5.5