Added KitPlayerDisconnectEvent

Added KitPlayerConnectEvent
Added KitPlayer
Added OfflineKitPlayer

Added giveKit(Player player, String kitId, boolean permissionCheck, boolean cooldownCheck, boolean putOnCooldown, boolean checkUpgrade) method
Added giveKit(Player player, Kit kit, boolean permissionCheck, boolean cooldownCheck, boolean putOnCooldown, boolean checkUpgrade) method

Added PlaceholderAPI support to Kit Available Names and Lores
Added PlaceholderAPI support to Kit On Cooldown Names and Lores
Added PlaceholderAPI support to Kit No Permission Names and Lores
Added PlaceholderAPI support to GUI item names and lores