Add bans in Arena

[slim vale]

As a player
I would like to introduce bans in Arena
In order to add variety to the team compositions

For example, if a character is in 90% of teams in the Arena game mode over a long duration, it could be banned from that mode for a certain period of time.

[shadow jungle]

This would be cool in Live Arena, both players pick 6 hero's then each bans one from the opponent.