add equals and hashCode methods for every DTO about article.
add equals and hashCode method for CodeDTO.
add equals and hashCode methods for every DTO about contest.
add equals and hashCode methods for every DTO about contest problem.
add equals and hashCode methods for ContestUserDTO.
add equals and hashCode methods for DepartmentDTO.
add equals and hashCode methods for LanguageDTO.
add equals and hashCode methods for every DTO about message.
add equals and hashCode methods for every DTO about problem.
add equals and hashCode methods for every DTO about status.
add equals and hashCode methods for every DTO about team.
add equals and hashCode methods for every DTO about team user.
add equals and hashCode methods for every DTO about user.
add equals and hashCode methods for UserSerialKeyDTO.
add uploadContestArchive service.
Merge pull request #124 from pfctgeorge/equals-and-hashCode-methods

equals and hashCode methods for DTOs
fix coding style.
Merge pull request #126 from pfctgeorge/contest-management

add uploadContestArchive service.
add createContestByArchiveFile method in ContestController.
Merge pull request #127 from pfctgeorge/contest-management

add createContestByArchiveFile method in ContestController.