Dissolution of marriage — Equitable distribution — Marital home — Marital gift presumption — Valuation — Trial court erred in unequally distributing marital home based on former husband’s assertion that the down payment on the home was made using funds former husband gratuitously received from his former employer during the marriage as a reward for former husband’s services prior to the marriage — Husband’s testimony alone that down payment was made with nonmarital funds was insufficient to overcome marital gift presumption — Trial court abused its discretion in valuing marital home based on an earlier appraisal rather than an appraisal which was completed closer to trial where record does not reflect that the home’s appreciation arose from any source other than market forces