Application of N.C.G.S. 14-306.4, prohibiting operation of electronic machines that conduct or promote a sweepstakes through use of an entertaining display, to plaintiffs' marketing system; whether the challenged system is exempt because it involves a game of skill, rather than a game of chance; whether the trial court erred in granting plaintiffs' motion for a preliminary injunction barring enforcement of gambling laws against them; whether appellate court has jurisdiction to hear sheriff's interlocutory appeal from the preliminary injunction because the appeal affects a substantial right