Merge pull request #73 from mzry1992/front-end-adjust

Front end adjust
clean up deprecated methods in picture service.
Merge pull request #75 from lyhypacm/persistence-cleanup

clean up deprecated methods in picture service.
delete maven configuration file and use gradle instead.
Merge pull request #77 from lyhypacm/persistence-cleanup

For #76 - delete maven configuration file and use gradle instead.
[UPDATE] Create team, contestTeam, teamUser table, and create patch script
[UPDATE] Remove ContestTeamInfo
[UPDATE] Add entities
[UPDATE] Set default value in database alert statement
[UPDATE] Modified register modal
[UPDATE] Update user editor
[UPDATE] Fix unique key in sql
[UPDATE] Add team service and team controller
[UPDATE] Add team register system
[UPDATE] Add custom hql query function
[UPDATE] Add user team list
[UPDATE] Send invitation where create new team
[UPDATE] Add allow state in team user
[UPDATE] Show inactive members in team list
[UPDATE] Show unreaded messages number