utils.ReservedWordsValidator is added. see HIVE-212
add javadoc @ UserApp
UserApp refactoring
add sign-up form validation - email duplication
the email validation added @ user info modify form
Merge pull request #52 from kjkmadness/HIVE-212

[HIVE-212] 로그인 ID 에 예약어 사용할수 없도록 처리