This changes events to store the database Account instead of an OfflinePlayer and deprecates any event method that uses/returns OfflinePlayer. This is necessary as Bukkit#getOfflinePlayer(String) queries Mojang for the UUID when the user was not found in the local cache. As we already store this information (name to UUID mapping) in our database we should not have no need to rely on querying Mojang. (This might make transactions fail for shop owners that haven't played before but that shouldn't really be an issue in most cases)
