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'
bugfix: course_code should be old_code not id
Merge branch 'iss7'
Merge branch 'master' into release