Remove meaningless query call on search()

  * local variable 'lectures' are overridden on any control path, so
    this assignment is meaningless.
Apply cache on search request without keyword (== listing some lectures)
개인정보 수정시에 확인 및 오류메시지 추가
추천과목 알고리즘을 SQL로 바꿔서 구현
Merge pull request #4 from hodduc/master

Timetable Search 성능 개선
Merge pull request #5 from sparcs-kaist/issue01

개인정보 수정시에 확인 및 오류메시지 추가
Revert "Remove meaningless query call on search()"

This reverts commit ca6cd6674abedbe0a038cbc61d65298ab5c25de7.
Revert unnecessary changes
Do not recommend course which user already have taken
Merge branch 'iss7'
Merge branch 'master' into release