11/18演習問題 => 修正
11/19, 11/20演習問題 => 追加
11/18-11/20の演習問題を修正
Merge remote-tracking branch 's13012/master'
Merge branch 'master' of https://github.com/KimiyukiYamauchi/oracle.2014
Merge branch 'master' of https://github.com/s13012/oracle_exercises