+ Added command /smcooldown

• Usage :
  Code (Text):

  /smcooldown <player/@a(all players online)/@everyone(all players)> <slot machine uuid/all> reset
• Permission : slotmachine.smcooldown

+ Background items are now fully customizable (not just material, meaning custom models now work)
+ Added a "copy machine uuid to clipboard" button under machine informations

* Fixed cooldowns starting even if player doesn't have enough currency