(Adds comment, details, and updates prices) By Melanie Burton MELBOURNE, Dec 7 (Reuters) - London copper edged up on Thursday but was still not far from two-month lows amid signs that growth in China's property and power sectors, both major copper consumers, is tapering into the year-end. Short-term demand for copper in China is weakening, said broker Argonaut in a report. Argonaut noted that China's mid-size cable producers had seen a decline in new orders for December, while i