Tournament short name usage

[halfa]

The tournament entity got a shortName parameter. This parameter is used:

• for displaying proper background on /tournament/{tournamentId}/public
• as tag on the event map to allow the players to pick a seat

22dd507 use the tournament short name to determine what background to use by capitalizing it and picking the correct file, but I'll change it to use the type instead.

As the shortName is basically tournamentType+tournamentYear should we replace it by a virtual attribute ?

[Teanan]

Also used for the captive portail API but yeah we can totally replace it by a virtual attribute.

Just, would not that be a problem with the tournament type "manual" ?