Merge pull request #60 from pfctgeorge/contest-registration

add DTO for contest user entity.
[persistence cleanup] clean up some deprecated DAO methods.
[travis CI] install all dependencies before testing.
Merge pull request #63 from lyhypacm/travis

[travis CI] install all dependencies before testing.
Merge pull request #62 from lyhypacm/persistence-cleanup

[persistence cleanup] clean up some deprecated DAO methods.
rename patches.
add column `studentId` to `contestTeamInfo` table